C++(씨쁠쁠)(cplusplus)-백준(baekjoon)(BaekJoon)코딩 4963번:섬의 개수(BFS) 답

#include <iostream>
#include <queue>
#include <algorithm>
using namespace std;
int d[51][51],a[51][51], cnt, dx[] = {0,0,-1,1,1,1,-1,-1}, dy[] = {-1,1,0,0,1,-1,1,-1 },w,h;
void BFS(int x, int y, int cnt)
{
    queue <pair<int, int> > q;
    q.push(make_pair(x, y));
    d[x][y] = cnt;
    while (!q.empty())
    {
        x = q.front().first;
        y = q.front().second;
        q.pop();
        for (int i = 0; i < 8; i++)
        {
            int nx = x + dx[i];
            int ny = y + dy[i];
            if (0 <= nx && nx < h && 0 <= ny && ny < w)
                if (d[nx][ny] == 0 && a[nx][ny] == 1)
                {
                    q.push(make_pair(nx, ny));
                    d[nx][ny] = cnt;
                }
        }
    }
}
int main() {
    while (1)
    {
        cin >> w >> h;
        if (w == 0 && h == 0) { return 0; }
        cnt = 0;
        for (int i = 0; i < 51; i++)//초기화
            for (int j = 0; j < 51; j++)
                a[i][j] = d[i][j] = 0;
        for (int i = 0; i < h; i++)//입력
            for (int j = 0; j < w; j++)
                cin >> a[i][j];
        for (int i = 0; i < h; i++)
            for (int j = 0; j < w; j++)
                if (a[i][j] == 1 && d[i][j] == 0)
                    BFS(i, j, ++cnt);
        cout << cnt << '\n';
    }
}