P1596 [USACO10OCT]Lake Counting S

 

# [USACO10OCT]Lake Counting S

## Title Description

Due to recent rains, water has pooled in various places in Farmer John's field, which is represented by a rectangle of N x M (1 <= N <= 100; 1 <= M <= 100) squares. Each square contains either water ('W') or dry land ('.'). Farmer John would like to figure out how many ponds have formed in his field. A pond is a connected set of squares with water in them, where a square is considered adjacent to all eight of its neighbors. Given a diagram of Farmer John's field, determine how many ponds he has.

Due to the recent rainfall , The rain collected in different parts of Farmer John's field . We use one NxM(1<=N<=100;1<=M<=100) The grid diagram shows . There is water in each grid ('W') Or dry land ('.'). A grid is connected to eight grids around it , A set of connected grids is regarded as a puddle . John wanted to find out how many puddles had formed in his field . Give a schematic diagram of John's field , Determine how many puddles there are .

## Input format

Line 1: Two space-separated integers: N and M \* Lines 2..N+1: M characters per line representing one row of Farmer John's field. Each character is either 'W' or '.'. The characters do not have spaces between them.

The first 1 That's ok ： An integer separated by two spaces ：N and M The first 2 Go to the first place N+1 That's ok ： Each row M Characters , Each character is 'W' or '.', They represent a row in a grid diagram . There is no space between characters .

## Output format

Line 1: The number of ponds in Farmer John's field.

a line ： Number of puddles

## Examples #1

### The sample input #1

```
10 12
W........WW.
.WWW.....WWW
....WW...WW.
.........WW.
.........W..
..W......W..
.W.W.....WW.
W.W.W.....W.
.W.W......W.
..W.......W.
```

### Sample output #1

```
3
```

## Tips

OUTPUT DETAILS: There are three ponds: one in the upper left, one in the lower left, and one along the right side.

【 Ideas 】

Direct set dfs Templates ,  Slightly modify You can pass .

【AC Code 】

#include<algorithm>
#include<cmath>
#include<cstdio>
#include<cstring>
#include<iomanip>
#include<iostream>
#include<map>
#include<queue>
#include<string>
#include<vector>
using namespace std;
const int N=1e3+10;
inline int fread()
{
	char ch=getchar();
	int n=0,m=1;
	while(ch<'0' or ch>'9')
	{
		if(ch=='-')m=-1;
		ch=getchar();
	}
	while(ch>='0' and ch<='9')n=(n<<3)+(n<<1)+ch-48,ch=getchar();
	return n*m;
}
void fwrite(int n)
{
	if(n>9)fwrite(n/10);
	putchar(n%10+'0');
}
int n,m,ans,a[N]={0,-1,-1,-1,0,0,1,1,1},b[N]={0,-1,0,1,-1,1,-1,0,1};
char ch[N][N];
void dfs(int x,int y)
{
	ch[x][y]=='.';// Searched 
	int z,p;
	for(int i=1;i<9;i++)
	{
		z=x+a[i],p=y+b[i];
		if(z<1 or z>n or p<1 or p>m or ch[z][p]=='.')continue;// Judge boundary condition 
		ch[z][p]='.',dfs(z,p);// eligible , take ch[z][p] Set as searched , Keep searching 
	}
	return;
}
signed main()
{
	n=fread(),m=fread();
	for(int i=1;i<=n;i++)
		for(int j=1;j<=m;j++)cin>>ch[i][j];
	for(int i=1;i<=n;i++)
		for(int j=1;j<=m;j++)
			if(ch[i][j]=='W')ans++,dfs(i,j);// If it's water , Record the number of puddles , And search 
	fwrite(ans);
	return 0;
}

After adjusting for a long time, I can't adjust it. I just changed a way of judging , And then it passed . 

Pay attention to it