Submission #2502844

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Source Code Expand

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <cmath>
#include <algorithm>
#include <vector>
#include <numeric>
#include <queue>
#include <map> 
#include <set>
#include <string>
#include <functional>
#include <list>
#include <random>
#include <time.h>
#define int long long
#define oku7 1000000007
#define MAXN (int)1e+5 * 2+1
#define LL_MAX 9223372036854775807	//ない環境用
using namespace std;
std::mt19937 mt((int)time(0));

int dx[4] = { 0, 1, 0,-1 }; // x軸方向への変位
int dy[4] = { 1, 0,-1, 0 }; // y軸方向への変位


struct uf_tree {
	std::vector<int> parent;
	int __size;
	uf_tree(int size_) : parent(size_, -1), __size(size_) {}
	void unite(int x, int y) {
		if ((x = find(x)) != (y = find(y))) {
			if (parent[y] < parent[x]) std::swap(x, y);
			parent[x] += parent[y];
			parent[y] = x;
			__size--;
		}
	}
	bool is_same(int x, int y) { return find(x) == find(y); }
	int find(int x) { return parent[x] < 0 ? x : parent[x] = find(parent[x]); }
	int size(int x) { return -parent[find(x)]; }
	int size() { return __size; }
};

int p[1000000];

signed main() {
	uf_tree uf(1000000);
	int N, M;
	cin >> N >> M;
	for (int i = 1; i <= N; i++) {
		int tmp;
		cin >> tmp;
		p[i] = tmp;
	}
	for (int i = 0; i < M; i++) {
		int x, y;
		cin >> x >> y;
		uf.unite(x, y);
	}
	int ans = 0;
	for (int i = 1; i <= N; i++) {
		if (uf.is_same(i, p[i])) ans++;
	}
	cout << ans << "\n";


	return 0;




}

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