Submission #317048

#	Time	Username	Problem	Language	Result	Execution time	Memory
317048		nandonathaniel	Traffic (IOI10_traffic)	C++14	100 / 100	1299 ms	151644 KiB

traffic

#include "traffic.h"
#include <bits/stdc++.h>
using namespace std;
const int MAXN=1e6+5;
vector<int> adj[MAXN];
int subtree[MAXN],atas[MAXN];

void dfs(int now,int par){
	atas[now]=par;
	for(auto nxt : adj[now]){
		if(nxt==par)continue;
		dfs(nxt,now);
		subtree[now]+=subtree[nxt];
	}
}

int LocateCentre(int N, int P[], int S[], int D[])
{
	for(int i=0;i<N;i++)subtree[i]=P[i];
    for(int i=0;i<N-1;i++){
    	adj[S[i]].push_back(D[i]);
    	adj[D[i]].push_back(S[i]);
	}
	dfs(0,-1);
	int ans=INT_MAX,idx;
	for(int i=0;i<N;i++){
		int ret=0;
		for(auto j : adj[i]){
			if(j==atas[i])ret=max(ret,subtree[0]-subtree[i]);
			else ret=max(ret,subtree[j]);
		}
//		cout << i << " " << ret << '\n';
		if(ret<ans){
			ans=ret;
			idx=i;
		}
	}
	return idx;
}

//int main(){
//	int N;
//	cin >> N;
//	int P[N],S[N-1],D[N-1];
//	for(int i=0;i<N;i++)cin >> P[i];
//	for(int i=0;i<N-1;i++)cin >> S[i] >> D[i];
//	cout << LocateCentre(N,P,S,D) << '\n';
//	return 0;
//}

Compilation message (stderr)

traffic.cpp: In function 'int LocateCentre(int, int*, int*, int*)':
traffic.cpp:38:9: warning: 'idx' may be used uninitialized in this function [-Wmaybe-uninitialized]
   38 |  return idx;
      |         ^~~

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