Submission #1111704

#	Time	Username	Problem	Language	Result	Execution time	Memory
1111704		ortsac	Paths (BOI18_paths)	C++17	100 / 100	865 ms	23216 KiB

paths

#include <bits/stdc++.h>

using namespace std;

#define int long long

int n, m, k;
vector<int> ord;
const int MAXN = 3e5 + 10;
vector<int> adj[MAXN];
int cor[MAXN];
int dp[MAXN];
int t;

void calc(int node, int i) {
    if (dp[node] != -1) return;
    if (i == (t - 1)) {
        dp[node] = 1;
        return;
    }
    dp[node] = 0;
    for (auto u : adj[node]) {
        if (cor[u] == ord[i + 1]) {
            calc(u, i + 1);
            dp[node] += dp[u];
        }
    }
}

int32_t main() {
    cin >> n >> m >> k;
    for (int i = 1; i <= n; i++) {
        cin >> cor[i];
    }
    for (int i = 0; i < m; i++) {
        int a, b;
        cin >> a >> b;
        adj[a].push_back(b);
        adj[b].push_back(a);
    }
    int ans = 0;
    for (int mask = 1; mask < (1LL << k); mask++) {
        ord.clear();
        for (int i = 0; i < k; i++) {
            if (mask & (1LL << i)) ord.push_back(i + 1);
        }
        t = ord.size();
        if (t == 1) continue;
        do {
            // do it now!!
            //for (auto u : ord) cout << u << " ";
            //cout << "\n";
            int currans = 0;
            memset(dp, -1, sizeof dp);
            for (int i = 1; i <= n; i++) {
                if (cor[i] == ord[0]) {
                    calc(i, 0);
                    currans += dp[i];
                }
            }
            //cout << "ans " << currans << "\n";
            ans += currans;
        } while (next_permutation(ord.begin(), ord.end()));
    }
    cout << ans << "\n";
}

• Subtask 1: 23 / 23
• Subtask 2: 20 / 20
• Subtask 3: 27 / 27
• Subtask 4: 30 / 30