Add a bunch of other problems.

Codeforces Round 843 (Div. 2)/D. Friendly Spiders.cpp

@@ -0,0 +1,232 @@
+/* Problem URL: https://codeforces.com/problemset/problem/1775/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;
+
+const int MAXN = 3e5 + 1;
+
+vi primes;
+int di[MAXN];
+
+void pre()
+{
+    fill(di, di + MAXN, 1);
+
+    nrep(i, 2, MAXN) {
+        if (di[i] != 1) {
+            continue;
+        }
+
+        for (int j = i; j < MAXN; j += i) {
+            di[j] = i;
+        }
+    }
+}
+
+#define TEST 0
+
+void solve()
+{
+    int n;
+    cin >> n;
+
+    vi a(n);
+    cin >> a;
+
+    int s, t;
+    cin >> s >> t;
+    s--, t--;
+
+    if (s == t) {
+        cout << "1\n";
+        cout << s + 1 << '\n';
+        return;
+    }
+
+    if (a[s] == 1 || a[t] == 1) {
+        cout << "-1\n";
+        return;
+    }
+
+    if (a[s] == a[t]) {
+        cout << "2\n";
+        cout << s + 1 << ' ' << t + 1 << '\n';
+        return;
+    }
+
+    V<bool> used(3e5 + 1);
+    used[a[s]] = true;
+    used[a[t]] = true;
+
+    vvi graph(MAXN + n);
+    auto getgraph = [&](int i) {
+        int now = a[i];
+        while (now > 1) {
+            int prev = di[now];
+            while (di[now] == prev) {
+                now /= di[now];
+            }
+            graph[prev].push_back(i + MAXN);
+            graph[i + MAXN].push_back(prev);
+        }
+    };
+
+    getgraph(s);
+    getgraph(t);
+
+    rep(i, n) {
+        // if ((i != s && a[i] == a[s]) || (i != t && a[i] == a[t])) {
+        //     continue;
+        // }
+        // pos[a[i]] = i;
+
+        if (used[a[i]]) {
+            continue;
+        }
+
+        used[a[i]] = true;
+        getgraph(i);
+    }
+
+    // nrep(i, 2, 3e5 + 1) {
+    //     if (pos[i] == -1) {
+    //         continue;
+    //     }
+    //
+    //     for (int j = i * 2; j <= 3e5; j += i) {
+    //         if (pos[j] == -1) {
+    //             continue;
+    //         }
+    //
+    //         graph[pos[i]].push_back(pos[j]);
+    //         graph[pos[j]].push_back(pos[i]);
+    //     }
+    // }
+
+    vi dis(MAXN + n, oo);
+    vi parent(MAXN + n, -1);
+    queue<int> q;
+    dis[s + MAXN] = 0;
+    q.push(s + MAXN);
+
+    while (!q.empty()) {
+        auto i = q.front();
+        q.pop();
+
+        for (auto j : graph[i]) {
+            if (dis[j] > dis[i] + 1) {
+                dis[j] = dis[i] + 1;
+                parent[j] = i;
+                q.push(j);
+            }
+        }
+    }
+
+    if (dis[t + MAXN] == oo) {
+        cout << "-1\n";
+        return;
+    }
+
+    vi ans;
+    int now = t + MAXN;
+    while (parent[now] != -1) {
+        if (now >= MAXN) {
+            ans.push_back(now - MAXN + 1);
+        }
+        now = parent[now];
+    }
+
+    ans.push_back(s + 1);
+    reverse(all(ans));
+    cout << ans.size() << '\n';
+    cout << ans;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}