Submission #43261

#	Time	Username	Problem	Language	Result	Execution time	Memory
43261		smu201111192	우호 조약 체결 (JOI14_friends)	C++14	0 / 100	122 ms	17280 KiB

friends

#include <iostream>
#include <cstdio>
#include <cassert>
#include <bitset>
#include <string>
#include <sstream>
#include <algorithm>
#include <set>
#include <numeric>
#include <cmath>
#include <map>
#include <vector>
#include <queue>
#include <stack>
#include <cstring>
#include <queue>
#include <numeric>
#include <iomanip>
#define ll long long
using namespace std;
const int MAXN = 400001;
int n,m,vis[MAXN],parent[MAXN],sz[MAXN];
vector<int> adj[MAXN];
int find(int u) { return u == parent[u] ? u : parent[u] = find(parent[u]); }
void mrg(int u,int v){
    u = find(u) , v = find(v);
    if(u == v)return;
    parent[u] = v;
    sz[v] += sz[u];
}
void dfs(int here,int root){
    vis[here] = 1;
    for(auto x:adj[here]){
        if(vis[x]) mrg(root,x);
        else{
            mrg(root,x);
            dfs(x,root);
        }
    }
}
int main(){
    ios::sync_with_stdio(false); cin.tie(0);
    cin >> n >> m;
    for(int i = 1; i <= n; i++){
        parent[i] = i;
        sz[i] = 1;
    }
    for(int i = 1; i <= m; i++){
        int u,v; cin >> u >> v;
        adj[u].push_back(v);
    }
    for(int i = 1; i <= n; i++){
        if(adj[i].size() >= 2 && !vis[i]){
            dfs(i,adj[i].front());
        }
    }
    long long ans = 0;
    for(int i = 1; i <= n; i++)if(i == find(i)) ans += 1LL * sz[i] * (sz[i] - 1);
    for(int i = 1; i <= n; i++){
        for(auto x:adj[i]){
            if(find(i) != find(x)) ans++;
        }
    }
    cout<<ans;
    return 0;
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 30
• Subtask 3: 0 / 65