Submission #342001

#	Time	Username	Problem	Language	Result	Execution time	Memory
342001		freshmintt	Traffic (IOI10_traffic)	C++11	50 / 100	587 ms	262148 KiB

traffic

#include <iostream>
#include <fstream>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <algorithm>
#include <cstdio>
#include <fstream>
#include <string.h>
#include <iterator> 
#include <list>
#include <cmath>
#include <math.h>
#include <unordered_map> 
#include <numeric>

using namespace std;
typedef long long ll;
typedef pair<ll,ll> pi;
vector<int> adj[1000001]; // change
ll people[1000001]; // change
multiset<ll> sums[1000001]; // change
ll subtree[1000001]; // change

void dfsSubtree(ll node, ll parent, ll parentSum) {
  // sums[node].insert(parentSum); // record the cumulative sum from root
  subtree[node] += people[node];
  for (auto u: adj[node]) {
    if (u != parent) { // traverse to the next node, adding on the parentSum
    // the subtree sum of the next node must be returned and added
    dfsSubtree(u, node, parentSum + people[node]);
    subtree[node] += subtree[u]; // subtree u is the sum for the child
    sums[node].insert(subtree[u]);
  }
}
}

void dfsParents(ll node, ll parent, ll parentSum) {
  sums[node].insert(parentSum);
  for (auto u : adj[node]) {
    if (u != parent) {

      ll res = subtree[0]-subtree[u];
      // cout << "going from:  "<< node << " to " << u << ", parentsum: " << res <<  endl;
      // must send parentSum = entire tree sum - dest node subtree
      
      dfsParents(u, node, res);
      // subtree[node] += subtree[u]; // subtree u is the sum for the child
      // sums[node].insert(subtree[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 ++) {
    people[i] = P[i];
  }
  // for (auto i : people) {
  //   cout << i << " ";
  // }
  // cout << endl;
  // for (auto item : adj) {
  //   for (auto i : item) {
  //     cout << i << " ";
  //   }
  //   cout << endl;
  // }
  dfsSubtree(0, -1, 0);
  
  // for (auto item : subtree) {
  //   cout << item << " " << endl;
  // }
  // cout << "now for all sums" << endl;
  dfsParents(0, -1, 0);
  // for (auto item : sums) {
  //   for (auto i : item)  {
  //     cout << i << " ";
  //   }
  //   cout << endl;
  // }
  ll minRoad = 1E12;
  ll city = -1;
  for (int i = 0; i < N; i++) {
    
    if (*sums[i].rbegin() < minRoad) {
      minRoad = *sums[i].rbegin();
      city = i;
    }
  }
  return city;
}

// int main() {
//   int P[5] = {10,10,10,20,20};
//   int S[4] = {1, 2, 2, 3};
//   int D[4] = {2, 0, 3, 4};
//   cout << LocateCentre(5, P, S, D);
// }

• Subtask 1: 25 / 25
• Subtask 2: 0 / 25
• Subtask 3: 25 / 25
• Subtask 4: 0 / 25