Submission #42336

#	Time	Username	Problem	Language	Result	Execution time	Memory
42336		minhtung0404	우호 조약 체결 (JOI14_friends)	C++14	35 / 100	99 ms	23284 KiB

friends

//https://oj.uz/problem/view/JOI14_friends

#include<bits/stdc++.h>
const int N = 1e5 + 5;
using namespace std;

vector <int> adj[N];

int n, m, pset[N], siz[N], ans;
bool check[N];

int findset(int i) {return ((pset[i] == i) ? i : pset[i] = findset(pset[i]));}

bool unionset(int i, int j){
    i = findset(i); j = findset(j);
    if (i == j) return false;
    siz[j] += siz[i];
    pset[i] = j;
    return true;
}

int main(){
    ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
    cin >> n >> m;
    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++) pset[i] = i, siz[i] = 1;
    for (int u = 1; u <= n; u++){
        if ((int)adj[u].size() >= 2){
            int x = adj[u][0]; check[x] = true;
            for (int i = 1; i < adj[u].size(); i++){
                int v = adj[u][i];
                check[v] = true;
                unionset(x, v);
            }
        }
    }
    queue <int> mq;
    for (int i = 1; i <= n; i++) if (check[i]) mq.push(i);
    while (mq.size()){
        int u = mq.front(); mq.pop();
        for (int i = 0; i < adj[u].size(); i++){
            int v = adj[u][i];
            if (!check[v]) check[v] = true, mq.push(v);
            unionset(u, v);
        }
    }
    for (int i = 1; i <= n; i++) if (pset[i] == i) ans += siz[i] * (siz[i] - 1);
    for (int i = 1; i <= n; i++) if (pset[i] == i && siz[i] == 1) ans += (int)adj[i].size();
    cout << ans << "\n";
}

Compilation message (stderr)

friends.cpp: In function 'int main()':
friends.cpp:33:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             for (int i = 1; i < adj[u].size(); i++){
                               ^
friends.cpp:44:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int i = 0; i < adj[u].size(); i++){
                           ^

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