[백준 1743: 음식물 피하기] - C++

www.acmicpc.net/problem/1743

1743번: 음식물 피하기

#include<iostream>
#include<string>
#include<queue>
#include<vector>
#include<algorithm>
using namespace std;
int map[100][100];
int check[100][100];
int n, m;
int k;
int dir[4][2] = {
	{-1,0}
	,{0,1}
	,{1,0}
	,{0,-1}
};
int cnt = 0;
void D(int _x,int _y)
{
	check[_x][_y] = 1;
	for (int i = 0; i < 4; i++)
	{
		int nextX = _x + dir[i][0];
		int nextY = _y + dir[i][1];

		if(nextX<1 || nextY<1 || n<nextX || m<nextY)
			continue;
		if (map[nextX][nextY] == 1 && check[nextX][nextY]==0)
		{
			cnt++;
			D(nextX, nextY);			
		}
	}
}
int main()
{
	cin >> n >> m >> k;
	if (n < 1 || m < 1 || k < 1)
	{
		cout << 0 << endl;
		return 0;
	}
	int x;
	int y;

	for (int i = 0; i < k; i++)
	{
		cin >> x >> y;

		map[x][y] = 1;
	}


	int max = cnt;
	for (int i = 1; i <= n; i++)
	{
		for (int j = 1; j <= m; j++)
		{			
			if (map[i][j] == 1 && check[i][j] == 0)
			{
				cnt = 1;
				D(i, j);
				if (max < cnt)
					max = cnt;
			}
			
		}
	}

	cout << max << endl;
	return 0;
}