[백준 2667] 단지번호 붙이기 (DFS) (C/C++)

#include <stdio.h>
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
 
int N;
int map[30][30];
int visited[30][30];
int houseNum;
int Size;
vector<int> complex;
 
int dx[4] = {-1, 1, 0, 0}; // 상하좌우 
int dy[4] = {0, 0, -1, 1}; // 상하좌우
 
int safe(int x, int y)
{
    if(x >= 0 && y >= 0 && x < N && y < N)
    {
        return 1;
    }
    else
    {
        return 0;
    }
}
 
void DFS(int x, int y, int color)
{
    for(int i = 0; i < 4; i++)
    {
        int xpos = x+dx[i];
        int ypos = y+dy[i];
        
        if(safe(xpos, ypos) == 1 && map[xpos][ypos] == 1 && visited[xpos][ypos] == 0)
        {
            visited[xpos][ypos] = color;
            DFS(xpos, ypos, color);
            Size++;
        }
    }
}
 
int main(void)
{
    // freopen("B2667_input.txt", "r", stdin);
    
    cin >> N;
    
    for(int i = 0; i < N; i++)
    {
        for(int j = 0; j < N; j++)
        {
            scanf("%1d", &map[i][j]);        
        }
    }
    
    for(int i = 0; i < N; i++)
    {
        for(int j = 0; j < N; j++)
        {
            if(map[i][j] == 1 && visited[i][j] == 0)
            {
                Size = 1;
                houseNum++;
                visited[i][j] = houseNum;
                DFS(i, j, houseNum);
                complex.push_back(Size);
            }
        }
    }
    
    cout << houseNum << endl;
    
    sort(complex.begin(), complex.end());
    for(int i = 0; i < complex.size(); i++)
    {
        cout << complex[i] << endl;
    }
        
    return 0;
}