Submission #540247

#	Time	Username	Problem	Language	Result	Execution time	Memory
540247		phathnv	Šarenlist (COCI22_sarenlist)	C++11	110 / 110	13 ms	472 KiB

Main

#include <bits/stdc++.h>
using namespace std;

const int N = 60;
const int M = 15;
const int MOD = 1e9 + 7;

struct DSU {
    int root[N];
    void init(int n) {
        for (int i = 0; i < n; ++i) {
            root[i] = -1;
        }
    }
    int findRoot(int u) {
        return (root[u] < 0? u : (root[u] = findRoot(root[u])));
    }
    bool unite(int u, int v) {
        u = findRoot(u);
        v = findRoot(v);
        if (u == v) {
            return false;
        }
        if (root[u] > root[v]) {
            swap(u, v);
        }
        root[u] += root[v];
        root[v] = u;
        return true;
    }
} dsu;

int n, m, k, h[N];
array<int, 2> par[N];
vector<array<int, 2>> adj[N];
vector<int> edges[M];

void Dfs(int u, int p) {
    for (auto &[v, id] : adj[u]) {
        if (v != p) {
            h[v] = h[u] + 1;
            par[v] = {u, id};
            Dfs(v, u);
        }
    }
}

int Pow(int n, int k) {
    if (k == 0) {
        return 1;
    }
    int res = Pow(n, k >> 1);
    res = 1ll * res * res % MOD;
    if (k & 1) {
        res = 1ll * res * n % MOD;
    }
    return res;
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cin >> n >> m >> k;
    for (int i = 0; i < n - 1; ++i) {
        int u, v;
        cin >> u >> v;
        --u, --v;
        adj[u].push_back({v, i});
        adj[v].push_back({u, i});
    }
    Dfs(0, -1);
    for (int i = 0; i < m; ++i) {
        int u, v;
        cin >> u >> v;
        --u, --v;
        while (u != v) {
            if (h[u] > h[v]) {
                swap(u, v);
            }
            edges[i].push_back(par[v][1]);
            v = par[v][0];
        }
    }
    int res = 0;
    for (int mask = 0; mask < (1 << m); ++mask) {
        int cnt = n - 1;
        dsu.init(n - 1);
        for (int i = 0; i < m; ++i) {
            if ((mask >> i) & 1) {
                for (int j = 1; j < (int) edges[i].size(); ++j) {
                    cnt -= dsu.unite(edges[i][j - 1], edges[i][j]);
                }
            }
        }
        if (__builtin_popcount(mask) % 2) {
            res = (res - Pow(k, cnt) + MOD) % MOD;
        } else {
            res = (res + Pow(k, cnt)) % MOD;
        }
    }
    cout << res << '\n';

    return 0;
}

Compilation message (stderr)

Main.cpp: In function 'void Dfs(int, int)':
Main.cpp:39:16: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   39 |     for (auto &[v, id] : adj[u]) {
      |                ^

• Subtask 1: 10 / 10
• Subtask 2: 15 / 15
• Subtask 3: 10 / 10
• Subtask 4: 10 / 10
• Subtask 5: 65 / 65