Submission #823211

#	Time	Username	Problem	Language	Result	Execution time	Memory
823211		t6twotwo	Wells (CEOI21_wells)	C++17	0 / 100	31 ms	340 KiB

wells

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int N, K;
    cin >> N >> K;
    vector<vector<int>> adj(N);
    for (int i = 0; i < N - 1; i++) {
        int x, y;
        cin >> x >> y;
        x--, y--;
        adj[x].push_back(y);
        adj[y].push_back(x);
    }
    for (int root = 0; root < N; root++) {
        vector<int> c(N);
        auto color = [&](auto f, int x, int p, int dep) -> void {
            if (dep % K == 0) {
                c[x] = 1;
            }
            for (int y : adj[x]) {
                if (y != p) {
                    f(f, y, x, dep + 1);
                }
            }
        };
        color(color, root, -1, 0);
        auto dfs = [&](auto dfs, int x, int p, int cnt, int dep) -> bool {
            if (dep == K - 1) {
                return cnt == 1;
            }
            for (int y : adj[x]) {
                if (y != p) {
                    if (!dfs(dfs, y, x, cnt + c[y], dep + 1)) {
                        return 0;
                    }
                }
            }
            return 1;
        };
        bool ok = 1;
        for (int i = 0; i < N; i++) {
            if (!dfs(dfs, i, -1, c[i], 0)) {
                ok = 0;
            }
        }
        if (ok) {
            cout << "YES\n1";
            return 0;
        }
    }
    cout << "NO\n0";
    return 6/22;
}

• Subtask 1: 0 / 30
• Subtask 2: 0 / 20
• Subtask 3: 0 / 20
• Subtask 4: 0 / 30