Submission #1162921

#	Time	Username	Problem	Language	Result	Execution time	Memory
1162921		brinton	Road Closures (APIO21_roads)	C++20	0 / 100	2093 ms	11140 KiB

roads

#include "roads.h"

#include <bits/stdc++.h>
using namespace std;
int k;
vector<long long> minimum_closure_costs(int N, vector<int> U,vector<int> V,vector<int> W) {
  // N^2 solution
  vector<vector<pair<int,int>>> edges;
  vector<long long> ans(N,0);
  edges.resize(N);
  for(int i = 0;i < N-1;i++){
    edges[U[i]].push_back({V[i],W[i]});
    edges[V[i]].push_back({U[i],W[i]});
  }
  vector<int> sv(N);
  iota(sv.begin(),sv.end(),0);
  sort(sv.begin(),sv.end(),[&](auto a,auto b){
    return edges[a].size() > edges[b].size();
  });
  ans[0] = N-1;
  vector<bool> vis(N,true);
  vector<int> deg(N);
  for(int k = 1;k < N;k++){
    for(auto v:sv){
      if(edges[v].size() <= k)break;
      vis[v] = false;
      deg[v] = edges[v].size();
    }
    function<void(int,int)> dfs = [&](int cur,int p){
      vis[cur] = true;
      for(auto [nxt,w]:edges[cur]){
        if(nxt == p)continue;
        if(edges[nxt].size() <= k)continue;
        dfs(nxt,cur);
      }
      ans[k] += max(0,deg[cur]-k);
      
      if(p != -1 && deg[cur] > k){
        deg[p]--;
      }
    };
    // cout << k << ":" << endl;
    for(auto v:sv){
      if(edges[v].size() <= k)break;
      if(vis[v])continue;
      dfs(v,-1);
    }
    // cout << endl;
  }
  return ans;
}

// // grader
// #include "roads.h"

// #include <cassert>
// #include <cstdio>

// #include <vector>

// int main() {
//   int N;
//   assert(1 == scanf("%d", &N));

//   std::vector<int> U(N - 1), V(N - 1), W(N - 1);
//   for (int i = 0; i < N - 1; ++i) {
//     assert(3 == scanf("%d %d %d", &U[i], &V[i], &W[i]));
//   }

//   std::vector<long long> closure_costs = minimum_closure_costs(N, U, V, W);
//   for (int i = 0; i < static_cast<int>(closure_costs.size()); ++i) {
//     if (i > 0) {
//       printf(" ");
//     }
//     printf("%lld",closure_costs[i]);
//   }
//   printf("\n");
//   return 0;
// }

• Subtask 1: 0 / 5
• Subtask 2: 0 / 7
• Subtask 3: 0 / 14
• Subtask 4: 0 / 10
• Subtask 5: 0 / 17
• Subtask 6: 0 / 25
• Subtask 7: 0 / 22