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2024 ICPC Asia Taichung Regional Contest (Unrated, Online Mirror, ICPC Rules, Preferably Teams)/D. Drunken Maze.cpp

@@ -0,0 +1,174 @@
+/* Problem URL: https://codeforces.com/problemset/problem/2041/D */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+
+void pre()
+{
+
+}
+
+#define TEST 0
+
+void solve()
+{
+    int n, m;
+    cin >> n >> m;
+
+    V<string> a(n);
+    cin >> a;
+
+    vvvvi dis(n, vvvi(m, vvi(4, vi(4, oo))));
+    auto find_s = [&]() -> pair<pair<int, int>, pair<int, int>> {
+        int si;
+        int sj;
+        int ei;
+        int ej;
+        rep(i, n) {
+            rep(j, m) {
+                if (a[i][j] == 'S') {
+                    si = i;
+                    sj = j;
+                    continue;
+                }
+
+                if (a[i][j] == 'T') {
+                    ei = i;
+                    ej = j;
+                }
+            }
+        }
+
+        return {{si, sj}, {ei, ej}};
+    };
+
+    auto [s, t] = find_s();
+    auto [si, sj] = s;
+    auto [ei, ej] = t;
+
+    queue<tuple<int, int, int, int>> q;
+    dis[si][sj][0][0] = 0;
+    dis[si][sj][1][0] = 0;
+    dis[si][sj][2][0] = 0;
+    dis[si][sj][3][0] = 0;
+    q.emplace(si, sj, 0, 0);
+    q.emplace(si, sj, 1, 0);
+    q.emplace(si, sj, 2, 0);
+    q.emplace(si, sj, 3, 0);
+    int ans = oo;
+    while (!q.empty()) {
+        auto [i, j, d, t] = q.front();
+        q.pop();
+
+        if (i == ei && j == ej) {
+            rmin(ans, dis[i][j][d][t]);
+        }
+
+        int add[][2] = {{0, 1}, {0, -1}, {1, 0}, {-1, 0}};
+        rep(k, 4) {
+            int id = i + add[k][0];
+            int jd = j + add[k][1];
+
+            int td = k == d ? t + 1 : 1;
+
+            if (a[id][jd] == '#' || td > 3 || dis[id][jd][k][td] <= dis[i][j][d][t] + 1) {
+                continue;
+            }
+
+            dis[id][jd][k][td] = dis[i][j][d][t] + 1;
+            q.emplace(id, jd, k, td);
+        }
+    }
+
+    cout << (ans == oo ? -1 : ans) << '\n';
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}

Codeforces Round 879 (Div. 2)/A. Unit Array.cpp

@@ -0,0 +1,127 @@
+/* Problem URL: https://codeforces.com/contest/1834/problem/A */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+
+void pre()
+{
+
+}
+
+#define TEST 1
+
+void solve()
+{
+    int n;
+    cin >> n;
+
+    array<int, 2> c = {0, 0};
+    rep(i, n) {
+        int r;
+        cin >> r;
+        c[r > 0]++;
+    }
+
+    int ans = 0;
+    if (c[1] < c[0]) {
+        int diff = (c[0] - c[1] + 1) >> 1;
+        ans += diff;
+        c[0] -= diff;
+    }
+
+    if (c[0] & 1) {
+        ans++;
+    }
+
+    cout << ans << '\n';
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}

Codeforces Round 879 (Div. 2)/B. Maximum Strength.cpp

@@ -0,0 +1,128 @@
+/* Problem URL: https://codeforces.com/contest/1834/problem/B */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+
+void pre()
+{
+
+}
+
+#define TEST 1
+
+void solve()
+{
+    string l, r;
+    cin >> l >> r;
+
+    int pad = r.size() - l.size();
+    string p(pad, '0');
+    p += l;
+    l = p;
+
+    int i = 0;
+    ll ans = 0;
+    while (i < r.size() && r[i] == l[i]) {
+        i++;
+    }
+
+    if (i == r.size()) {
+        cout << "0\n";
+        return;
+    }
+
+    ans += r[i] - l[i];
+    ans += (r.size() - i - 1) * 9;
+
+    cout << ans << '\n';
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}

Codeforces Round 879 (Div. 2)/C. Game with Reversing.cpp

@@ -0,0 +1,133 @@
+/* Problem URL: https://codeforces.com/contest/1834/problem/C */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+
+void pre()
+{
+
+}
+
+#define TEST 1
+
+void solve()
+{
+    int n;
+    cin >> n;
+    string a, b;
+    cin >> a >> b;
+
+    int c1 = 0;
+    int c2 = 0;
+    rep(i, n) {
+        c1 += a[i] != b[i];
+        c2 += a[i] != b[n - i - 1];
+    }
+
+    if (c1 == 0) {
+        cout << "0\n";
+        return;
+    }
+
+    if (c1 == 1) {
+        cout << "1\n";
+        return;
+    }
+
+    if (c2 == 0) {
+        cout << "2\n";
+        return;
+    }
+
+    cout << min(c1 * 2 - 1 + (~c1 & 1), c2 * 2 - 1 + (c2 & 1)) << '\n';
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}

Codeforces Round 879 (Div. 2)/D. Survey in Class.cpp

@@ -0,0 +1,164 @@
+/* Problem URL: https://codeforces.com/problemset/problem/1834/D */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+
+void pre()
+{
+
+}
+
+#define TEST 1
+
+void solve()
+{
+    int n, m;
+    cin >> n >> m;
+
+    V<pair<ll, ll>> a(n);
+
+    pair<ll, ll> a1 = {oo, oo};
+    pair<ll, ll> a2 = {0, 0};
+    pair<ll, ll> a3 = {0, oo};
+
+    auto sz = [&](pair<ll, ll> a) {
+        return a.second - a.first + 1;
+    };
+
+    repv(i, a) {
+        cin >> i.first >> i.second;
+        if (a1.second > i.second || (a1.second == i.second && a1.first > i.first)) {
+            a1 = i;
+        }
+
+        if (a2.first < i.first || (a2.first == i.first && a2.second < i.second)) {
+            a2 = i;
+        }
+
+        if (sz(i) <= sz(a3)) { 
+            a3 = i;
+        }
+    }
+
+    auto calc = [&](pair<ll, ll> a, pair<ll, ll> b) {
+        if (a.first > b.first) {
+            swap(a, b);
+        }
+
+        auto [al, ar] = a;
+        auto [bl, br] = b;
+
+        if (al <= bl && ar >= br) {
+            return sz(a) - sz(b);
+        }
+
+        if (al <= br && bl <= ar) {
+            return max(sz({al, bl}), sz({ar, br})) - 1;
+        }
+
+        return max(sz(a), sz(b));
+    };
+
+    ll ans = 0;
+    repv(i, a) {
+        rmax(ans, calc(a1, i) * 2);
+    }
+    repv(i, a) {
+        rmax(ans, calc(a2, i) * 2);
+    }
+    repv(i, a) {
+        rmax(ans, calc(a3, i) * 2);
+    }
+
+    cout << ans << '\n';
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}

Codeforces Round 996 (Div. 2)/C. The Trail.cpp

@@ -0,0 +1,156 @@
+/* Problem URL: https://codeforces.com/problemset/problem/2055/C */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+
+void pre()
+{
+
+}
+
+#define TEST 1
+
+void solve()
+{
+    int n, m;
+    cin >> n >> m;
+
+    string s;
+    cin >> s;
+
+    vvl a(n, vl(m));
+    cin >> a;
+
+    vvl ss(2);
+    ss[0].resize(n);
+    ss[1].resize(m);
+
+    rep(i, n) {
+        rep(j, m) {
+            ss[0][i] += a[i][j];
+            ss[1][j] += a[i][j];
+        }
+    }
+
+    int i = s[0] == 'D';
+    int j = s[0] == 'R';
+    a[0][0] = s[0] == 'D' ? -ss[0][0] : -ss[1][0];
+    ss[0][0] += a[0][0];
+    ss[1][0] += a[0][0];
+    ll ch = 0;
+    while (i < n - 1 || j < m - 1) {
+        // int pi = i - (s[i + j - 1] == 'D');
+        // int pj = j - (s[i + j - 1] == 'R');
+
+        // int ch = s[pi + pj] == 'R';
+        if (s[i + j] == 'R') {
+            ll s = ss[1][j];
+            a[i][j] = -s;
+            ss[0][i] -= s;
+            ss[1][j] -= s;
+            j++;
+            continue;
+        }
+
+        ll s = ss[0][i];
+        a[i][j] = -s;
+        ss[0][i] -= s;
+        ss[1][j] -= s;
+        i++;
+    }
+
+    ll diff = ss[0][n - 1];
+    a[n - 1][m - 1] = -diff;
+
+    cout << a;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}

Educational Codeforces Round 143 (Rated for Div. 2)/D. Triangle Coloring.cpp

@@ -0,0 +1,156 @@
+/* Problem URL: https://codeforces.com/problemset/problem/1795/D */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+
+void pre()
+{
+
+}
+
+#define TEST 0
+
+void solve()
+{
+    int n;
+    cin >> n;
+    vl a(n);
+    cin >> a;
+
+    const ll mod = 998244353;
+    ll mul = 1;
+    for (int i = 0; i < n; i += 3) {
+        ll ma = *max_element(a.begin() + i, a.begin() + i + 3);
+        ll mi = *min_element(a.begin() + i, a.begin() + i + 3);
+
+        int ca = count(a.begin() + i, a.begin() + i + 3, ma);
+        int ci = count(a.begin() + i, a.begin() + i + 3, mi);
+
+        if (ca == 3) {
+            (mul *= 3) %= mod;
+            continue;
+        }
+
+        if (ca == 2) {
+            continue;
+        }
+
+        if (ci == 2) {
+            (mul *= 2) %= mod;
+        }
+    }
+
+    auto fpow = [&](ll a, ll p) {
+        ll ans = 1;
+
+        rep(i, 61) {
+            if ((p >> i) & 1) {
+                (ans *= a) %= mod;
+            }
+            (a *= a) %= mod;
+        }
+
+        return ans;
+    };
+
+    vl fact(n + 1);
+
+    fact[0] = 1;
+    nrep(i, 1, n + 1) {
+        fact[i] = fact[i - 1] * i % mod;
+    }
+
+    n /= 3;
+    ll comb = fact[n] * fpow(fact[n / 2], mod - 2) % mod * fpow(fact[n / 2], mod - 2) % mod;
+    cout << mul * comb % mod << '\n';
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}

Educational Codeforces Round 188 (Rated for Div. 2)/A. Passing the Ball.cpp

@@ -0,0 +1,121 @@
+/* Problem URL: https://codeforces.com/contest/2204/problem/A */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+
+void pre()
+{
+
+}
+
+#define TEST 1
+
+void solve()
+{
+    int n;
+    cin >> n;
+
+    string s;
+    cin >> s;
+
+    int now = 0;
+    vi a(n);
+    a[0] = 1;
+
+    rep(i, n) {
+        now += (s[now] == 'R') - (s[now] == 'L');
+        a[now] = 1;
+    }
+
+    cout << accumulate(all(a), 0) << '\n';
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}

Educational Codeforces Round 188 (Rated for Div. 2)/B. Right Maximum.cpp

@@ -0,0 +1,129 @@
+/* Problem URL: https://codeforces.com/contest/2204/problem/B */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+
+void pre()
+{
+
+}
+
+#define TEST 1
+
+void solve()
+{
+    int n;
+    cin >> n;
+
+    vi a(n);
+    cin >> a;
+
+    vvi pos(n);
+    rep(i, n) {
+        pos[a[i] - 1].push_back(i);
+    }
+
+    int ans = 0;
+    int cur = n;
+
+    for (int i = n - 1; i >= 0; i--) {
+        for (int j = pos[i].size() - 1; j >= 0; j--) {
+            if (pos[i][j] < cur ) {
+                cur = pos[i][j];
+                ans++;
+            }
+        }
+    }
+
+    cout << ans << '\n';
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}

Educational Codeforces Round 188 (Rated for Div. 2)/C. Spring.cpp

@@ -0,0 +1,118 @@
+/* Problem URL: https://codeforces.com/contest/2204/problem/C */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+
+void pre()
+{
+
+}
+
+#define TEST 1
+
+void solve()
+{
+    ll a, b , c, d;
+    cin >> a >> b >> c >> d;
+
+    ll ab = lcm(a, b);
+    ll ac = lcm(a, c);
+    ll bc = lcm(c, b);
+    ll abc = lcm(ab, ac);
+
+    vl ans(3);
+    ans[0] = d / abc * 2 + (d / ab + d / ac - d / abc * 2) * 3 + (d / a - d / ab - d / ac + d / abc) * 6;
+    ans[1] = d / abc * 2 + (d / ab + d / bc - d / abc * 2) * 3 + (d / b - d / ab - d / bc + d / abc) * 6;
+    ans[2] = d / abc * 2 + (d / bc + d / ac - d / abc * 2) * 3 + (d / c - d / bc - d / ac + d / abc) * 6;
+    cout << ans;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}

Educational Codeforces Round 188 (Rated for Div. 2)/D. Alternating Path.cpp

@@ -0,0 +1,179 @@
+/* Problem URL: https://codeforces.com/contest/2204/problem/D */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+
+void pre()
+{
+
+}
+
+#define TEST 1
+
+void solve()
+{
+    int n, m;
+    cin >> n >> m;
+
+    vvi graph(n);
+    while (m--) {
+        int a, b;
+        cin >> a >> b;
+        a--, b--;
+        graph[a].push_back(b);
+        graph[b].push_back(a);
+    }
+
+    vi dis(n, oo);
+    function<pair<int, bool>(int)> bfs = [&](int i) -> pair<int, bool> {
+        dis[i] = 0;
+        queue<int> q;
+        q.push(i);
+        bool pos = true;
+        int sz = 1;
+
+        while (!q.empty()) {
+            auto i = q.front();
+            q.pop();
+
+            repv(j, graph[i]) {
+                if (dis[j] > dis[i] + 1) {
+                    dis[j] = dis[i] + 1;
+                    q.push(j);
+                    sz++;
+                    continue;
+                }
+
+                if ((dis[j] & 1) == (dis[i] & 1)) {
+                    pos = false;
+                }
+            }
+        }
+
+        return {sz, pos};
+    };
+
+    V<bool> vis(n);
+
+    int ans = 0;
+    rep(i, n) {
+        if (dis[i] != oo) {
+            continue;
+        }
+
+        auto [c, p] = bfs(i);
+
+        if (!p) {
+            continue;
+        }
+
+        array<int, 2> co = {0, 0};
+        function<void(int, int)> dfs = [&](int i, int g) {
+            co[g]++;
+            vis[i] = true;
+
+            repv(j, graph[i]) {
+                if (vis[j]) {
+                    continue;
+                }
+
+                dfs(j, g^1);
+            }
+        };
+
+        dfs(i, 0);
+        ans += max(co[0], co[1]);
+    }
+
+    cout << ans << '\n';
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}

TODO.md

@@ -133,6 +133,10 @@ Official divs from codeforces
 
 		I got everything I need to do it, but I still need to find the equation to solve
 		every single case...
+	
+	- [X] [D. Survey in Class](https://codeforces.com/problemset/problem/1834/D)
+
+		Almost did it, I think I got what it needs to do it, but ran out of time.
 
 - Div 3