제출 #427669

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
427669		shubham20_03	Traffic (IOI10_traffic)	C++17	0 / 100	14 ms	23756 KiB

traffic

#include <bits/stdc++.h>
#include "traffic.h"
using namespace std;
#define FAST ios_base::sync_with_stdio(false); cin.tie(NULL)

vector<int> adj[1000000];
int tot_peo[1000000], ans[1000000], peo[1000000];

// refer kartik arora's dp on trees youtube videos
// idea is taken from his tree distance ii video

void dfs1(int u, int p = -1) {
	tot_peo[u] = peo[u];
	for (int v : adj[u])
		if (v != p) {
			dfs1(v, u);
			tot_peo[u] += tot_peo[v];
		}
}

void dfs2(int u, int p = -1) {
	ans[u] = 0;
	for (int v : adj[u])
		if (v != p)
			ans[u] = max(ans[u], tot_peo[v]);

	if (p != -1)
		ans[u] = max(ans[u], tot_peo[0] - tot_peo[u]);

	for (int v : adj[u])
		if (v != p)
			dfs2(v, u);
}

int LocateCentre(int N, int P[], int S[], int D[]) {
	for (int i = 0; i < N - 1; i++) {
		adj[S[i]].push_back(D[i]);
		adj[D[i]].push_back(S[i]);
	}

	for (int i = 0; i < N; i++)
		peo[i] = P[i];

	dfs1(0);
	dfs2(0);

	int mn = 2e9;
	for (int i = 0; i < N; i++)
		mn = min(mn, ans[i]);

	return mn;
}

• Subtask 1: 0 / 25
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