Submission #2560167

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Source Code Expand

#include <iostream>
#include <cstdio>
#include <cmath>
#include <vector>
#include <list>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <string>
#include <utility>
#include <algorithm>
#include <functional>
#include <deque>
#define INF 1e9
#define MOD 1000000007
#define mod(x) ((x % MOD) + MOD) % MOD
#define MAX_N 100001
#define MAX_M 100001

using namespace std;

typedef long long ll;
typedef pair<int,int> P;

int par[MAX_N];
int myrank[MAX_N];

void init(int n)
{
  for (int i = 0; i < n; i++) {
    par[i] = i;
    myrank[i] = 0;
  }
}

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

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

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

int main() {
  int N, M;
  int p[MAX_N];
  int x[MAX_M]; int y[MAX_N];
  cin >> N >> M;
  for (int i = 0; i < N; i++) {
    cin >> p[i]; p[i]--;
  }
  for (int i = 0; i < M; i++) {
    cin >> x[i] >> y[i]; x[i]--; y[i]--;
  }

  init(N);
  for (int i = 0; i < M; i++) {
    unite(x[i], y[i]);
  }

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

  cout << ans << endl;

  return 0;
}

Submission Info

Judge Result