Submission #339608

#	Time	Username	Problem	Language	Result	Execution time	Memory
339608		TheYellowFlash	Traffic (IOI10_traffic)	C++17	100 / 100	1120 ms	151604 KiB

traffic

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

#define ll int64_t
#define all(x) x.begin(), x.end()

const int mxN = 1e6+3;
vector<int> adj[mxN];
vector<ll> ans;
vector<ll> subtree(mxN, 0);
ll sum;

void dfs(int edge, int prev){
     for(auto& e: adj[edge]){
          if(e == prev) continue;
          dfs(e, edge);
          subtree[edge] += subtree[e];
          ans[edge] = max(ans[edge], subtree[e]);
     }
     ans[edge] = max(ans[edge], sum - subtree[edge]);
}

int LocateCentre(int N, int pp[], int S[], int D[]) {
     ans.resize(N);
     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){
          subtree[i] += pp[i];
          sum += pp[i];
     }

     dfs(0, 0);
     
     return min_element(all(ans)) - ans.begin();
}

// subtree[i] originally == node weight
// Increment it each time by weights of its subnodes
// Answer could be max(ans, sum(of all weights) - ans) 

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