[백준] 1012 - 유기농 배추(설명X)

#include <cstdio>
 
bool isOnField(int x, int y, int width, int height) {
    if (x < 0)
        return false;
    else if (y < 0)
        return false;
    else if (x >= width)
        return false;
    else if (y >= height)
        return false;
    return true;
}
 
void DFS(int** arr, int x, int y, int width, int height) {
    if (!isOnField(x, y, width, height) || arr[x][y] == 0)
        return;
    
    arr[x][y] = 0;
    DFS(arr, x, y - 1, width, height);
    DFS(arr, x - 1, y, width, height);
    DFS(arr, x, y + 1, width, height);
    DFS(arr, x + 1, y, width, height);
}
 
int main() {
    int T;
    scanf("%d", &T);
    for (int i = 0; i < T; i++) {
        int M, N, K, num = 0;
        scanf("%d %d %d", &M, &N, &K);
        int** field = new int* [M];
        for (int j = 0; j < M; j++)
            field[j] = new int[N] {0, };
        for (int j = 0; j < K; j++) {
            int x, y;
            scanf("%d %d", &x, &y);
            field[x][y] = 1;
        }
        for (int a = 0; a < M; a++) {
            for (int b = 0; b < N; b++) {
                if (field[a][b] == 1) {
                    DFS(field, a, b, M, N);
                    num++;
                }
            }
        }
        printf("%d\n", num);
        for (int j = 0; j < M; j++)
            delete[] field[j];
        delete[] field;
    }
}