Lake Counting

Time Limit: 1000MS Memory Limit: 65536K
Total Submissions: 59523 Accepted: 28958

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

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W........WW.
.WWW.....WWW
....WW...WW.
.........WW.
.........W..
..W......W..
.W.W.....WW.
W.W.W.....W.
.W.W......W.
..W.......W.

Sample Output

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3

Hint

OUTPUT DETAILS:

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

Source

USACO 2004 November

题目大意: 计算出相连的’W’有多少块

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#include <iostream>
#include <vector>
//#include <bits/stdc++.h>
using namespace std;
const int maxn=105;
char mapa[maxn][maxn];
int N,M;
void dfs(int x,int y){
    mapa[x][y]='.';
    int tempx;
    int tempy;
    for(int i=-1;i<=1;i++){
        for(int j=-1;j<=1;j++){
            tempx=x+i;
            tempy=y+j;
            if(tempx>=0&&tempx<N&&tempy>=0&&tempy<M&&mapa[tempx][tempy]=='W'){
                dfs(tempx,tempy);
            }
        }
    }
    return ;

}
int main() {
   // std::cout << "Hello, World!" << std::endl;

   cin>>N>>M;
  // vector<vector<char> > map(N,(vector<char> (M)));
   for(int i=0;i<N;i++){
       for(int j=0;j<M;j++){
           char temp;
           cin >> temp;
           mapa[i][j]=temp;
       }
   }
//cout<<"here"<<endl;
   int cnt=0;
   for(int i=0;i<N;i++){
       for(int j=0;j<M;j++){
           if(mapa[i][j]=='W'){
               dfs(i,j);
//               cout<<cnt<<endl;
//               for(int i=0;i<N;i++){
//                   for(int j=0;j<M;j++){
//
//                       cout<<mapa[i][j]<<" ";
//                   }
//                   cout<<endl;
//               }
               cnt+=1;
           }
       }
   }

   cout<<cnt<<endl;




   return 0;
}