[알고리즘 C++] 백준 4963 - 섬의 개수

//섬의 개수 DFS
//출처O

#include <iostream>
#include <cstring>
#include <queue>
using namespace std;
int map[50][50], visit[50][50];
int dx[8] = { 1,1,0,-1,-1,-1,0,1 }, dy[8] = { 0,1,1,1,0,-1,-1,-1 };
int w, h;

void dfs(int y, int x) {
	for (int i = 0; i < 8; i++) {
	int nextX = x + dx[i];
	int nextY = y + dy[i];
	if (nextX < 0 || nextY < 0 || nextX >= w || nextY >= h)continue; 
	if (!visit[nextY][nextX] && map[nextY][nextX]) { 
		visit[nextY][nextX] = 1;
		dfs(nextY, nextX);
		}		
	}	
}

int main() {
	ios_base::sync_with_stdio(0); cin.tie(NULL);
    	while (1) {
        	int cnt = 0;
        	cin >> w >> h;
        	if (!w && !h)break; 
        	for (int i = 0; i < h; i++) {
            		for (int j = 0; j < w; j++) {
                    	cin >> map[i][j];
                	}
            	}	
        	for (int i = 0; i < h; i++) { 
            		for (int j = 0; j < w; j++) {
                   		if (!visit[i][j] && map[i][j]) {
                   		visit[i][j] = 1;
       	           		dfs(i, j);
                    		cnt++; 
                		}
               		}	
           	}
		cout << cnt << "\n";
         	memset(visit, 0, sizeof(visit));  
		}		
}