Submission #401426

#	Time	Username	Problem	Language	Result	Execution time	Memory
401426		Hazem	Duathlon (APIO18_duathlon)	C++14	23 / 100	126 ms	19120 KiB

count_triplets

#include <bits/stdc++.h>
using namespace std;
 
#define LL long long
#define F first
#define S second
#define pii pair<int,int>
#define piii pair<pair<int,int>,int>

const int N = 2e5+10;
const int M = 200;
const LL INF = 1e9;
const LL LINF = 1e14;
const LL MOD = 1e9+7;
const double PI = 3.141592653589793;

vector<int>adj[N];
LL sizes[N],depth[N],n,m;
bool vis[N];

int dfs1(int i,int pre){

    vis[i] = 1;
    sizes[i] = vis[i] = 1;
    for(auto x:adj[i])
        if(!vis[x])
            depth[x] = depth[i]+1,sizes[i] += dfs1(x,i);

    return sizes[i];
}

LL C(LL n,LL k){

    LL ret = 1,d = 1;
    for(int i=n;i>=n-k+1;i--)
        ret = ret*i,d *= n-i+1;

    return ret/d;
}

LL dfs(int i,int pre,int sz){

    LL ret = 0;
    for(auto x:adj[i]){
        if(depth[x]<depth[i])continue;
        ret += dfs(x,i,sz);
    }

    LL cur = sz-1;
    for(auto x:adj[i]){
        
        if(depth[x]>depth[i]||x==pre){
            LL v = 0;
            if(x==pre)v = sz-sizes[i];
            else v = sizes[x];
            ret += (cur-v)*v;
        }

        else {
            LL len = depth[i]-depth[x]+1;
            ret += C(len,3)*2;
            ret += C(len-1,2)*(sz-sizes[x]+1);
        }
    }

    return ret;
}

int main(){

    //freopen("out.txt","w",stdout);
    //freopen("out.txt","r",stdin);

    scanf("%d%d",&n,&m);

    for(int i=1;i<=m;i++){
        int u,v;
        scanf("%d%d",&u,&v);
        adj[u].push_back(v);
        adj[v].push_back(u);        
    }

    LL ans = 0;
    for(int i=1;i<=n;i++)
        if(!vis[i]){
            int sz = dfs1(i,i);
            ans += dfs(i,i,sz);
        }

    printf("%lld\n",ans);
}   

Compilation message (stderr)

count_triplets.cpp: In function 'int main()':
count_triplets.cpp:74:13: warning: format '%d' expects argument of type 'int*', but argument 2 has type 'long long int*' [-Wformat=]
   74 |     scanf("%d%d",&n,&m);
      |            ~^    ~~
      |             |    |
      |             int* long long int*
      |            %lld
count_triplets.cpp:74:15: warning: format '%d' expects argument of type 'int*', but argument 3 has type 'long long int*' [-Wformat=]
   74 |     scanf("%d%d",&n,&m);
      |              ~^     ~~
      |               |     |
      |               int*  long long int*
      |              %lld
count_triplets.cpp:74:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   74 |     scanf("%d%d",&n,&m);
      |     ~~~~~^~~~~~~~~~~~~~
count_triplets.cpp:78:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   78 |         scanf("%d%d",&u,&v);
      |         ~~~~~^~~~~~~~~~~~~~

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