Submission #2559283

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Source Code Expand

#include<bits/stdc++.h>

using namespace std;
vector<int>dsu;

int parent(int a){
    if(dsu[a] == a) return a;
    return parent(dsu[a]);
}


void join(int a, int b){
    int pa = parent(a);
    int pb = parent(b);
    dsu[pa] = pb;
}

int main(){

    ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL); cout.precision(20);


    int n, m, a, b;
    cin >> n >> m;
    vector<int>p(n);
    dsu = vector<int>(n);
    for(int i = 0; i < n; i++){
        cin >> p[i];
        p[i]--;
    }

    for(int i = 0; i < n; i++) dsu[i] = i;
    for(int i = 0; i < m; i++){
        cin >> a >> b;
        --a; --b;
        join(a,b);
    }
    int ans = 0;
    for(int i = 0; i < n; i++){
        ans += parent(p[i]) == parent(i); 
    }

    cout << ans << endl;
}   

Submission Info

Judge Result