[백준]11724 - 연결 요소의 개수

#include <iostream>
using namespace std;
 
void find(int** grp, int* arr, int size, int val) {
    arr[val] = 1;
    for (int pos = 0; pos <= size; pos++) {
        if (grp[val][pos] == 1 && arr[pos] == 0) {
            find(grp, arr, size, pos);
        }
    }
}
 
int main() {
    int N, M, num = 0;
    cin >> N >> M;
    int* arr = new int[N + 1]{ 0, };
    int** grp = new int*[N + 1];
    for (int i = 1; i < N + 1; i++)
        grp[i] = new int[N + 1]{ 0, };
    for (int i = 0; i < M; i++) {
        int u, v;
        cin >> u >> v;
        grp[u][v] = 1;
        grp[v][u] = 1;
    }
    for (int i = 1; i <= N; i++) {
        if (arr[i] == 0) {
            num++;
            find(grp, arr, N, i);
        }
    }
    cout << num << endl;
}