Submission #55691

#	Time	Username	Problem	Language	Result	Execution time	Memory
55691		mohammad_kilani	Duathlon (APIO18_duathlon)	C++17	31 / 100	176 ms	15332 KiB

count_triplets

#include <bits/stdc++.h>
using namespace std;
#define mod 1000000007
#define oo 1000000000
const int N = 100010;
int n , m , u , v , dfs_low[N] , dfs_num[N] , dfs_cnt = 0 , all[N], comp[N] , comp_cnt = 0;
vector< int > g[N] ; 
bool vis[N];
long long ans = 0;

void DFS2(int node){
    vis[node] = true;
    comp[node] = comp_cnt;
    all[comp_cnt]++;
    for(int i=0;i<g[node].size();i++){
        if(!vis[g[node][i]])
            DFS2(g[node][i]);
    }
}

pair<int,int> DFS(int node,int prnt){
    dfs_low[node] = dfs_num[node] = ++dfs_cnt;
    int num1 = 1 , num2 = 1 , num3 = all[comp[node]] - 1;
    pair<int,int> tmp;
    for(int i=0;i<g[node].size();i++){
        if(g[node][i] == prnt) continue;
        if(dfs_num[g[node][i]] != 0){
            dfs_low[node] = min(dfs_low[node],dfs_num[g[node][i]]);
            continue;
        }
        tmp = DFS(g[node][i],node);
        num3 -= tmp.first;
        num1 += tmp.first;
        dfs_low[node] = min(dfs_low[node],dfs_low[g[node][i]]);
        if(dfs_low[g[node][i]] >= dfs_num[node]){
            ans += (long long)tmp.first * num3 * 2;
            ans += (long long)(tmp.second + 1) * tmp.second * (tmp.second - 1);
            ans += (long long)tmp.second * (tmp.second - 1) * num3 * 2;
        }
        else{
            num2 += tmp.second;
        }

    }
    return make_pair(num1,num2);
}



int main(){
    scanf("%d%d",&n,&m);
    for(int i=0;i<m;i++){
        scanf("%d%d",&u,&v);
        g[u].push_back(v);
        g[v].push_back(u);
    }
    for(int i=1;i<=n;i++){
        if(!vis[i]){
            DFS2(i);
            comp_cnt++;
        }
    }
    for(int i=1;i<=n;i++){
        if(dfs_num[i] == 0)
            DFS(i,-1);
    }
    cout << ans << endl;
    return 0;
}

Compilation message (stderr)

count_triplets.cpp: In function 'void DFS2(int)':
count_triplets.cpp:15:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<g[node].size();i++){
                 ~^~~~~~~~~~~~~~~
count_triplets.cpp: In function 'std::pair<int, int> DFS(int, int)':
count_triplets.cpp:25:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<g[node].size();i++){
                 ~^~~~~~~~~~~~~~~
count_triplets.cpp: In function 'int main()':
count_triplets.cpp:51:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d",&n,&m);
     ~~~~~^~~~~~~~~~~~~~
count_triplets.cpp:53:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d",&u,&v);
         ~~~~~^~~~~~~~~~~~~~

• Subtask 1: 0 / 5
• Subtask 2: 0 / 11
• Subtask 3: 8 / 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