More problems

2026-04-28 13:14:58 -03:00
parent 3ac1071724
commit 97658bef82
10 changed files with 1523 additions and 0 deletions
--- a/Preferred)/K.
+++ b/Preferred)/K.
@@ -0,0 +1,182 @@
+/* Problem URL: https://codeforces.com/problemset/problem/1912/K */
+
+#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;
+
+const ll mod = 998244353;
+constexpr int MAXN = 2e5 + 10;
+ll fact[MAXN];
+ll inv[MAXN];
+ll invf[MAXN];
+
+ll comb(ll n, ll k) {
+    return fact[n] * invf[k] % mod * invf[n - k] % mod;
+}
+
+void pre()
+{
+    fact[0] = 1;
+    nrep(i, 1, MAXN) {
+        fact[i] = fact[i - 1] * i % mod;
+    }
+
+    inv[1] = 1;
+    nrep(i, 2, MAXN) {
+        inv[i] = (mod - mod / i) * inv[mod % i] % mod;
+    }
+
+    invf[0] = 1;
+    nrep(i, 1, MAXN) {
+        invf[i] = invf[i - 1] * inv[i] % mod;
+    }
+}
+
+#define TEST 0
+
+void solve()
+{
+    int n;
+    cin >> n;
+    vl a(n);
+    ll c = 0;
+    repv(i, a) {
+        cin >> i;
+        c += ~i & 1;
+    }
+
+    ll ans = 0;
+    nrep(i, 3, c + 1) {
+        (ans += comb(c, i)) %= mod;
+    }
+    int seq[] = {1, 0, 1};
+
+    vvvl memo(n, vvl(3, vl(2, -1)));
+    auto init = [&]() {
+        rep(i, n) {
+            rep(j, 3) {
+                rep(k, 2) {
+                    memo[i][j][k] = -1;
+                }
+            }
+        }
+    };
+
+    function<ll(int, int, int)> dp = [&](int i, int c, int val) {
+        if (i >= n) {
+            return 0LL;
+        }
+
+        ll &ans = memo[i][c][val];
+        if (ans != -1) {
+            return ans;
+        }
+
+        ans = 0;
+        if (seq[c] == (a[i] & 1)) {
+            (ans += dp(i + 1, (c + 1) % 3, val || (c == 2)) + (val || (c == 2))) %= mod;
+        }
+        (ans += dp(i + 1, c, val)) %= mod;
+        return ans;
+    };
+
+    (ans += dp(0, 0, 0)) %= mod;
+    seq[0] = 0;
+    seq[1] = 1;
+    init();
+    (ans += dp(0, 0, 0)) %= mod;
+    seq[0] = 1;
+    seq[2] = 0;
+    init();
+    (ans += dp(0, 0, 0)) %= mod;
+
+    cout << ans << '\n';
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}