Sarthak product subgraph

Miscellaneous/Diameter-Division/problemLink

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+https://codedrills.io/contests/icpc-mathura-kanpur-2022-regional-round/problems/diameter-division

Miscellaneous/Product-Subgraph/problemLink

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+https://codedrills.io/contests/icpc-gwalior-pune-2021-regional-round---mirror/problems/product-constrained-subgraphs

Miscellaneous/Product-Subgraph/sarthak.cpp

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+#include <iostream>
+#include <vector>
+#include <cmath>
+using namespace std;
+const int mod = 998244353;
+void combine(vector<int> &f, vector<int> &F, vector<int> &g, vector<int> &G, int P)
+{
+    vector<int> h(f.size()), H(h.size());
+    for (int i = 1; i < f.size(); ++i)
+    {
+        for (int j = 1; (i * j) < f.size(); ++j)
+        {
+            h[i * j] = (h[i * j] + ((f[i] - f[i - 1]+mod) * 1ll * (g[j] - g[j - 1]+mod))) % mod;
+        }
+    }
+    for (int i = 1; i < h.size(); ++i)
+    {
+        h[i] += h[i - 1];
+        if (h[i] >= mod)
+            h[i] -= mod;
+    }
+    for (int i = 1; i < F.size(); ++i)
+    {
+        int z = sqrt((P / i));
+        for (int j = 1; j <= z; ++j)
+        {
+            if (i * j < F.size())
+                H[i] = (H[i] + ((f[j] - f[j - 1]+mod) * 1ll * G[i * j])) % mod;
+            else
+                H[i] = (H[i] + ((f[j] - f[j - 1]+mod) * 1ll * g[P / (i * j)])) % mod;
+        }
+        for (int j = 1; j <= z; ++j)
+        {
+            if (i * j < F.size())
+                H[i] = (H[i] + ((g[j] - g[j - 1]+mod) * 1ll * F[i * j])) % mod;
+            else
+                H[i] = (H[i] + ((g[j] - g[j - 1]+mod) * 1ll * f[P / (i * j)])) % mod;
+        }
+        H[i] = (H[i] - ((f[z] * 1ll * g[z])%mod)) % mod;
+        if (H[i] < 0)
+            H[i] += mod;
+    }
+    for (int i = 0; i < f.size(); ++i)
+    {
+        f[i] += h[i];
+        if (f[i] >= mod)
+            f[i] -= mod;
+    }
+    for (int i = 0; i < F.size(); ++i)
+    {
+        F[i] += H[i];
+        if (F[i] >= mod)
+            F[i] -= mod;
+    }
+}
+pair<vector<int>, vector<int>> dfs(int u, int p, vector<vector<int>> &g, vector<int> &a, int H, int T, int P, int &ans)
+{
+    vector<int> f(H), F(T);
+    for (int i = a[u]; i < H; ++i)
+        f[i] = 1;
+    for (int i = 1; i < T; ++i)
+        F[i] = a[u] <= (P / i);
+    for (auto v : g[u])
+    {
+        if (v != p)
+        {
+            pair<vector<int>, vector<int>> child = dfs(v, u, g, a, H, T, P, ans);
+            combine(f, F, child.first, child.second, P);
+        }
+    }
+    ans += F[1];
+    if (ans >= mod)
+        ans -= mod;
+    return make_pair(f, F);
+}
+void solve()
+{
+    int n, p;
+    cin >> n >> p;
+    vector<int> a(n);
+    for (auto &x : a)
+        cin >> x;
+    vector<vector<int>> g(n);
+    for (int i = 1; i < n; ++i)
+    {
+        int u, v;
+        cin >> u >> v;
+        --u;
+        --v;
+        g[u].push_back(v);
+        g[v].push_back(u);
+    }
+	int H = sqrt(p)+1;
+    auto calT = [&](int h)
+    {
+        return (p + h) / h;
+    };
+    while (H * log(H) < (2 * sqrtl(p *1ll* calT(H))))
+        ++H;
+    int T = max(calT(H), 2);
+    int ans = 0;
+    dfs(0, 0, g, a, H, T, p, ans);
+    cout << ans << "\n";
+}
+int main()
+{
+    ios_base::sync_with_stdio(false);
+    cin.tie(NULL);
+    int t;
+    cin >> t;
+    while (t--)
+        solve();
+}

Persistance/Roll-backs/problemLink

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+https://codeforces.com/contest/1858/problem/E2

Recurrence/DP/Digit-DP/Kth-Number/problemLink

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+https://codedrills.io/contests/icpc-mathura-kanpur-2022-regional-round/problems/kth-number

Recurrence/Function-Generation/Binary-Digit-Escaping/problemLink

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+https://codedrills.io/contests/icpc-mathura-kanpur-2022-regional-round/problems/binary-digit-escaping

Recurrence/Function-Generation/Prefect-Strings/problemLink

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+https://codedrills.io/contests/icpc-asia-west-continent-final-contest-2022/problems/perfect-strings