Submission #598328

#	Time	Username	Problem	Language	Result	Execution time	Memory
598328		acatmeowmeow	Traffic (IOI10_traffic)	C++11	100 / 100	1262 ms	198220 KiB

traffic

#include "traffic.h"

#include <bits/stdc++.h>

using namespace std;

void dfs(int u, int e, vector<vector<int>>&adj, vector<int>&dp, int P[]) {
	dp[u] += P[u];
	for (auto&v : adj[u]) {
		if (v == e) continue;
		dfs(v, u, adj, dp, P);
		dp[u] += dp[v];
	}
}

void reroot(int u, int e, vector<vector<int>>&adj, vector<int>&dp, int P[], int&mn, int&ans) {
	int cur = 0;
	for (auto&v : adj[u]) cur = max(cur, dp[v]);
	if (cur < mn) mn = cur, ans = u;
	for (auto&v : adj[u]) {
		if (v == e) continue;
		dp[u] -= dp[v], dp[v] += dp[u];
		reroot(v, u, adj, dp, P, mn, ans);
		dp[v] -= dp[u], dp[u] += dp[v];
	}
}

int LocateCentre(int N, int P[], int S[], int D[]) {
	// build adjacency array
	vector<vector<int>> adj(N + 5);
	for (int i = 0; i < N - 1; i++) adj[S[i]].push_back(D[i]), adj[D[i]].push_back(S[i]);
	// dp
	vector<int> dp(N + 5);
	dfs(0, -1, adj, dp, P);
	// solve for all roots
	int mn = 1e18, ans = -1;
	reroot(0, -1, adj, dp, P, mn, ans);
	return ans;
}

Compilation message (stderr)

traffic.cpp: In function 'int LocateCentre(int, int*, int*, int*)':
traffic.cpp:36:11: warning: overflow in conversion from 'double' to 'int' changes value from '1.0e+18' to '2147483647' [-Woverflow]
   36 |  int mn = 1e18, ans = -1;
      |           ^~~~

• Subtask 1: 25 / 25
• Subtask 2: 25 / 25
• Subtask 3: 25 / 25
• Subtask 4: 25 / 25