Submission #1081566

#	Time	Username	Problem	Language	Result	Execution time	Memory
1081566		vjudge1	Mag (COCI16_mag)	C++17	84 / 120	893 ms	262144 KiB

mag

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

bool operator < (const pair<int, int>& x, const pair<int, int>& y) {
	return 1LL * x.first * y.second < 1LL * x.second * y.first;
}

int main() {
	int n; cin >> n;
	vector<vector<int>> adj(n + 1, vector<int>());
	for (int i = 1, a, b; i < n; i++) {
		cin >> a >> b;
		adj[a].push_back(b);
		adj[b].push_back(a);
	}
	vector<int> val(n + 1, 0);
	vector<vector<int>> dp(n + 1, vector<int>()), dp_pref(n + 1, vector<int>()), dp_suf(n + 1, vector<int>());
	vector<int> dp2(n + 1, 0);
	for (int i = 1; i <= n; i++) cin >> val[i];
	function<void(int, int)> dfs1 = [&](int u, int par) -> void {
		if (u != 1 && adj[u].size() == 1) {
			dp[u].emplace_back(0);
			dp_pref[u].emplace_back(0);
			dp_suf[u].emplace_back(0);
			return;
		}
		for (int v: adj[u]) {
			if (v == par) { dp[u].push_back(0); continue; }
			dfs1(v, u);
			if (val[v] != 1) dp[u].push_back(0);
			else dp[u].push_back(dp_suf[v][1] + 1);
		}
		int k = adj[u].size();
		dp_pref[u].assign(k + 2, 0);
		dp_suf[u].assign(k + 2, 0);
		for (int j = 1; j <= k; j++) dp_pref[u][j] = max(dp_pref[u][j - 1], dp[u][j - 1]);
		for (int j = k; j >= 1; j--) dp_suf[u][j] = max(dp_suf[u][j + 1], dp[u][j - 1]);
	};
	dfs1(1, 0);
	function<void(int, int)> dfs2 = [&](int u, int par) {
		if (u != 1 && adj[u].size() == 1) return;
		int k = adj[u].size();
		for (int j = 1; j <= k; j++) {
			if (adj[u][j - 1] == par) continue;
			int v = adj[u][j - 1];
			if (val[u] != 1) dp2[v] = 0;
			else dp2[v] = max(dp2[u], max(dp_pref[u][j - 1], dp_suf[u][j + 1])) + 1;
			dfs2(v, u);
		}
	};
	dfs2(1, 0);
	pair<int, int> ans = {1e9 + 7, 1};
	for (int i = 1; i <= n; i++) {
		pair<int, int> tmp = {val[i], dp_suf[i][1] + dp2[i] + 1};
		if (tmp < ans) ans = tmp;
	}
	int g = __gcd(ans.first, ans.second);
	ans.first /= g; ans.second /= g;
	cout << ans.first << '/' << ans.second;
	return 0;
}

• Subtask 1: 12 / 12
• Subtask 2: 12 / 12
• Subtask 3: 12 / 12
• Subtask 4: 0 / 12
• Subtask 5: 0 / 12
• Subtask 6: 12 / 12
• Subtask 7: 0 / 12
• Subtask 8: 12 / 12
• Subtask 9: 12 / 12
• Subtask 10: 12 / 12