Submission #104525

#	Time	Username	Problem	Language	Result	Execution time	Memory
104525		tc_abd	Duathlon (APIO18_duathlon)	C++14	0 / 100	169 ms	10972 KiB

count_triplets

#include <bits/stdc++.h>
using namespace std;
int n,m,curr=1;
int psum[100009];
bool done[100009];
vector < int > v[100009];
void dfs(int node){
    psum[node] = curr++;
    done[node] = 1;
    for(int i=0;i<v[node].size();i++){
        int u = v[node][i];
        if(!done[u]) dfs(u);
    }
}
int main(){
    cin>>n>>m;
    for(int i=0;i<m;i++){
        int a,b;
        cin>>a>>b;
        a--;b--;
        v[a].push_back(b);
        v[b].push_back(a);
    }
    int x = 0,y = 0;
    bool z = 0;
    for(int i=0;i<n;i++){
        if(v[i].size() == 1 && z == 0){x = i;z=1;continue;}
        if(v[i].size() == 1 && z == 1){y = i;break;}
    }
    dfs(x);
    int ans = 0;
    for(int i=0;i<n;i++){
        int x = psum[y] - psum[i];
        int y = psum[i] - 1;
        if(x != 0) ans += ((x-1)*x)/2;
        if(y != 0) ans += ((y-1)*y)/2;
    }
  	cout<<ans<<endl;
}

Compilation message (stderr)

count_triplets.cpp: In function 'void dfs(int)':
count_triplets.cpp:10:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<v[node].size();i++){
                 ~^~~~~~~~~~~~~~~

• 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