洛谷P1451 求细胞数量 题解

//求连通块，搜过的染色，避免二次搜索
#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <string>
using namespace std;
int m, n, ans;
char c[105][105];
bool f[105][105];
int d[4][2] = { {-1,0},{0,-1},{1,0},{0,1} };//上左下右
bool in(int x, int y)//是否在图内
{
	return 0 <= x && x < m && 0 <= y && y < n;
}
bool dfs(int x, int y)
{
	f[x][y] = true;
	for (int i = 0;i < 4; i++)
	{
		int tx = x + d[i][0];
		int ty = y + d[i][1];
		if (in(tx, ty) && c[tx][ty] != '0' && !f[tx][ty])
		{
			dfs(tx, ty);
		}
	}
	return true;
}
int main()
{
	cin >> m >> n;
	for (int i = 0; i < m; i++)
	{
		cin >> c[i];
	}
	for (int i = 0; i < m; i++)
	{
		for (int j = 0; j < n; j++)
		{
			if (c[i][j] != '0' && !f[i][j])
			{
				ans++;dfs(i, j);
			}
		}
	}
	cout << ans << endl;
	return 0;
}