Submission #402154

#	Time	Username	Problem	Language	Result	Execution time	Memory
402154		A_D	Duathlon (APIO18_duathlon)	C++14	0 / 100	120 ms	11580 KiB

count_triplets

#include <bits/stdc++.h>

#define int long long

using namespace std;
const int N=1e5+100;
vector<int> g[N];
int dep[N];
int a[N];
int n,ans;
void dfs2(int u,int p)
{
    for(auto x:g[u]){
        if(x==p)continue;
        dep[x]=dep[u]+1;
        dfs2(x,u);
        a[u]+=a[x];
    }
}
void dfs(int u,int p,int ann)
{
    ans+=ann-(n);
    //cout<<u<<" "<<ann<<endl;
    ans+=1;
    for(auto x:g[u]){
        if(x==p)continue;
        dfs(x,u,ann+(n-a[x])-a[x]);
    }
}
void solve()
{
    int m,ann=0;
    cin>>n>>m;
    if(m!=n-1)assert(0);
    for(int i=1;i<=n;i++)a[i]=1;
    while(m--){
        int a,b;
        cin>>a>>b;
        g[a].push_back(b);
        g[b].push_back(a);
    }
    dfs2(1,1);
    for(int i=1;i<=n;i++){
        ann+=dep[i];
    }
    dfs(1,1,ann);
    cout<<ans<<endl;
}

main()
{
    int t=1;
//    cin>>t;
    while(t--)solve();
}

Compilation message (stderr)

count_triplets.cpp:52:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   52 | main()
      | ^~~~

• 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