Submission #734857

#	Time	Username	Problem	Language	Result	Execution time	Memory
734857		keisuke6	Duathlon (APIO18_duathlon)	C++14	0 / 100	90 ms	6660 KiB

count_triplets

#include <bits/stdc++.h>
using namespace std;
bool sub3(vector<vector<int>> &G){
  for(int i=0;i<G.size();i++)if(G[i].size() > 2) return false;
  return true;
}
struct Unionfind{
  vector<int> par, siz;
  //初期化
  Unionfind(int n) : par(n,-1) , siz(n,1) {}
  int root(int x) {
    if(par[x] == -1) return x;
    else return par[x] = root(par[x]);
  }
  bool issame(int x,int y) {
    return root(x) == root(y);
  }
  bool unite(int x, int y){
    x = root(x); y = root(y);
    if(x ==  y) return false;
    if(siz[x] < siz[y]) swap(x,y);
    par[y] =  x;
    siz[x] += siz[y];
    return  true;
  }
  int size(int x) {
    return siz[root(x)];
  }
};
int main(){
  int N,M;
  cin>>N>>M;
  vector<vector<int>> G(N);
  for(int i=0;i<M;i++){
    int a,b;
    cin>>a>>b;
    a--;
    b--;
    G[a].push_back(b);
    G[b].push_back(a);
  }
  if(sub3(G)){
    Unionfind uf(N);
    for(int i=0;i<N;i++){
      for(int x:G[i]) uf.unite(i,x);
    }
    map<int,int> mm;
    for(int i=0;i<N;i++)for(int x:G[i]) mm[uf.root(x)]++;
    map<int,int> m;
    for(int i=0;i<N;i++) m[uf.root(i)]++;
    long long ans = 0;
    for(auto x:m){
      int n = x.second;
      if(mm[x.first] == n) for(long long i=2;i<n;i++) ans += (i-1)*n*2;
      else for(long long i=2;i<n;i++) ans += (i-1)*(n-i)*2;
    }
    cout<<ans<<endl;
    return 0;
  }
}

Compilation message (stderr)

count_triplets.cpp: In function 'bool sub3(std::vector<std::vector<int> >&)':
count_triplets.cpp:4:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    4 |   for(int i=0;i<G.size();i++)if(G[i].size() > 2) return false;
      |               ~^~~~~~~~~

• Subtask 1: 0 / 5
• Subtask 2: 0 / 11
• Subtask 3: 0 / 8
• Subtask 4: 0 / 10
• Subtask 5: 0 / 13
• Subtask 6: 0 / 15
• Subtask 7: 0 / 20
• Subtask 8: 0 / 8
• Subtask 9: 0 / 10