池塘问题（深搜）

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题目：

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.

Input

* 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.

Output

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

Sample Input

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

Sample Output

Hint

大体意思就是找W被.分成了多少块。

下面是一个正确的代码。

#include<stdio.h>#define MAXN 110char ww[MAXN][MAXN];int vis[MAXN][MAXN];int f=0;int n,m;void search(int x,int y){    if(x<0||x>=n||y<0||y>=m||vis[x][y]||ww[x][y]=='.') return;    vis[x][y]=1;    search(x+1,y);    search(x+1,y+1);search(x+1,y-1);search(x-1,y);search(x-1,y+1);search(x-1,y-1);search(x,y+1);search(x,y-1);}main(){char z;int i,j;int x,y;for(i=0;i<MAXN;i++){for(j=0;j<MAXN;j++)vis[i][j]=0;}scanf("%d%d",&n,&m);    scanf("%s",ww[i]);}for(i=0;i<n;i++){for(j=0;j<m;j++){if(!vis[i][j]&&ww[i][j]=='W'){search(i,j);f++;}}}printf("%d\n",f);}

下面是一个错误的代码：

#include<stdio.h>#define MAXN 110char ww[MAXN][MAXN];int vis[MAXN][MAXN];int f=0;void search(int x,int y){vis[x][y]=1;if(!vis[x][y]&&ww[x][y]=='W'){search(x+1,y);search(x+1,y+1);search(x+1,y-1);search(x-1,y);search(x-1,y+1);search(x-1,y-1);search(x,y+1);search(x,y-1);}}main(){int i,j;int n,m;int x,y;for(i=0;i<MAXN;i++){for(j=0;j<MAXN;j++)vis[i][j]=0;}scanf("%d%d",&n,&m);getchar();for(i=0;i<MAXN;i++){for(j=0;j<MAXN;j++)ww[i][j]='.';}for(i=1;i<=n;i++){for(j=1;j<=m;j++)getchar(ww[i][j]);getchar();}for(i=1;i<=n;i++){for(j=1;j<=m;j++){printf("%c\n",ww[i][j]);if(!vis[i][j]&&ww[i][j]=='W'){search(i,j);f++;}}}printf("%d\n",f);}

上面的代码中有两处错误，但是我不知道具体哦原因。

一处是gerchar的使用会使编译器报错。

另一处是深搜函数有问题，可能不执行递归。

没有进行调试，具体原因不清楚。

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