Submission #393371

#	Time	Username	Problem	Language	Result	Execution time	Memory
393371		huukhang	Traffic (IOI10_traffic)	C++11	100 / 100	1208 ms	156788 KiB

traffic

// - Only when necessary :d
// #pragma GCC optimize("Ofast")
// #pragma GCC optimize("unroll-loops")

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

const int inf = 2e9;

int sum = 0;
int a[1000005];
vector<vector<int>> g;
int sz[1000005], congest[1000005];

void dfs(int s, int p) {
	sz[s] = a[s];
	for (auto v : g[s]) {
		if (v != p) {
			dfs(v, s);
			sz[s] += sz[v];
			congest[s] = max(congest[s], sz[v]);
		}
	}

	congest[s] = max(congest[s], sum - sz[s]);
}

int LocateCentre(int n, int p[], int s[], int d[]) {
	for (int i = 0; i < n; ++i) a[i] = p[i];

	g.resize(n);
	for (int i = 0; i < n - 1; ++i) {
		g[s[i]].push_back(d[i]);
		g[d[i]].push_back(s[i]);
	}

	for (int i = 0; i < n; ++i) sum += a[i];

	dfs(0, -1);

	int mn = inf, ans;
	for (int i = 0; i < n; ++i) {
		if (mn > congest[i]) {
			mn = congest[i];
			ans = i;
		}
	}

	return ans;
}

Compilation message (stderr)

traffic.cpp: In function 'int LocateCentre(int, int*, int*, int*)':
traffic.cpp:50:9: warning: 'ans' may be used uninitialized in this function [-Wmaybe-uninitialized]
   50 |  return ans;
      |         ^~~

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