백준 4963 섬의 개수

https://www.acmicpc.net/problem/4963

 

#include <iostream>
#include <vector>

using namespace std;

int w, h;
vector<vector<int>> map;
vector<vector<bool>> visited;

// 8방향 (상, 하, 좌, 우 + 대각선)
int dx[8] = { -1, -1, -1, 0, 0, 1, 1, 1 };
int dy[8] = { -1, 0, 1, -1, 1, -1, 0, 1 };

void DFS(int x, int y)
{
    visited[y][x] = true;

    for (int i = 0; i < 8; ++i)
    {
        int nx = x + dx[i];
        int ny = y + dy[i];

        if (nx >= 0 && ny >= 0 && nx < w && ny < h)
        {
            if (!visited[ny][nx] && map[ny][nx] == 1)
            {
                DFS(nx, ny);
            }
        }
    }
}

int main()
{
    while (true)
    {
        cin >> w >> h;
        if (w == 0 && h == 0) break;

        map = vector<vector<int>>(h, vector<int>(w));
        visited = vector<vector<bool>>(h, vector<bool>(w, false));

        for (int y = 0; y < h; ++y)
        {
            for (int x = 0; x < w; ++x)
            {
                cin >> map[y][x];
            }
        }

        int islandCount = 0;

        for (int y = 0; y < h; ++y)
        {
            for (int x = 0; x < w; ++x)
            {
                if (map[y][x] == 1 && !visited[y][x])
                {
                    DFS(x, y);
                    ++islandCount;
                }
            }
        }

        cout << islandCount << endl;
    }

    return 0;
}