Submission #3928744

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Source Code Expand

//include
//------------------------------------------
#include <vector>
#include <list>
#include <map>
#include <unordered_map>
#include <climits>
#include <set>
#include <unordered_set>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>
#include <queue>
#include <random>
#include <complex>
#include <regex>

using namespace std;

#define SHOW_VECTOR(v) {std::cerr << #v << "\t:";for(const auto& xxx : v){std::cerr << xxx << " ";}std::cerr << "\n";}
#define SHOW_MAP(v){std::cerr << #v << endl; for(const auto& xxx: v){std::cerr << xxx.first << " " << xxx.second << "\n";}}

struct UnionFind {
    vector<int> par;
    vector<int> sizes;

    UnionFind(int n) :
            par(n), sizes(n, 1) {
        for (int i = 0; i < n; i++) par[i] = i;
    }

    int find(int x) {
        if (x == par[x]) return par[x];
        else return par[x] = find(par[x]);
    }

    void unite(int x, int y) {
        x = find(x);
        y = find(y);
        if (x == y) return;
        if (sizes[x] < sizes[y]) swap(x, y);
        sizes[x] += sizes[y];
        par[y] = x;
    }

    bool same(int x, int y) {
        return find(x) == find(y);
    }

    int getSizes(int x) {
        return sizes[x];
    }

};

int main() {

    int N, M;
    cin >> N >> M;

    vector<int> p(N);
    for (int i = 0; i < N; i++)cin >> p[i], p[i]--;

    UnionFind UF(N);

    for (int i = 0; i < M; i++) {
        int x, y;
        cin >> x >> y;
        x--, y--;
        UF.unite(x, y);
    }

    int ans = 0;
    for (int i = 0; i < N; i++) {
        if (UF.same(i, p[i])) ans++;
    }


    cout << ans << endl;

}

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