Submission #520647

#	Time	Username	Problem	Language	Result	Execution time	Memory
520647		Sohsoh84	Paths (BOI18_paths)	C++17	100 / 100	1033 ms	70960 KiB

paths

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<ll, ll> pll;

#define all(x)			(x).begin(),(x).end()
#define X			first
#define Y			second
#define sep			' '
#define endl			'\n'
#define debug(x)		cerr << #x << ": " <<  x << endl;

const ll MAXN = 1e6 + 10;

int n, m, k, C[MAXN];
ll dp[MAXN], ans = 0;
vector<int> adj[MAXN], vert[MAXN];

int main() {
	ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
	cin >> n >> m >> k;
	for (int i = 1; i <= n; i++) {
		cin >> C[i];
		C[i]--;
		vert[C[i]].push_back(i);
	}

	for (int i = 0; i < m; i++) {
		int u, v;
		cin >> u >> v;
		adj[u].push_back(v);
		adj[v].push_back(u);
	}

	for (int mask = 0; mask < (1 << k); mask++) {
		if (__builtin_popcount(mask) < 2) continue;
		vector<int> vec;
		for (int i = 0; i < k; i++)
			if (mask & (1 << i))
				vec.push_back(i);

		int sz = __builtin_popcount(mask);
		do {
			memset(dp, 0, sizeof dp);
			for (int e : vert[vec.front()])
				dp[e] = 1;

			for (int i = 1; i < sz; i++) {
				int ind = vec[i];
				for (int v : vert[ind]) {
					for (int u : adj[v]) {
						if (C[u] == vec[i - 1]) {
							dp[v] += dp[u];
						}
					}
					
					if (i == sz - 1) ans += dp[v];
				}
			}
		} while (next_permutation(all(vec)));
	}

	cout << ans << endl;
	return 0;
}

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