poj 2386
2015-07-22 18:18
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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
Sample Output
Hint
OUTPUT DETAILS:
There are three ponds: one in the upper left, one in the lower left,and one along the right side.
题意:
'W'表示积水,‘.’表示没有积水,上下左右对角表示连通的(八连通),连通的部分称为一个水洼给你一个图,要你求出水洼个数。
思路:
用DFS,进行递归,遇到’W标记起来,下次不再检索。循环即可。
代码:
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 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
3
Hint
OUTPUT DETAILS:
There are three ponds: one in the upper left, one in the lower left,and one along the right side.
题意:
'W'表示积水,‘.’表示没有积水,上下左右对角表示连通的(八连通),连通的部分称为一个水洼给你一个图,要你求出水洼个数。
思路:
用DFS,进行递归,遇到’W标记起来,下次不再检索。循环即可。
代码:
#include<cstdio> using namespace std; const int maxn=105; int N,M; char field[maxn][maxn]; void dfs(int x,int y) { field[x][y]='.'; for(int dx=-1; dx<=1; dx++) { for(int dy=-1; dy<=1; dy++) { int nx=x+dx,ny=y+dy; if(nx>=0&&nx<N&&ny>=0&&ny<M&&field[nx][ny]=='W') dfs(nx,ny); } } return ; } int main() { int sum=0; scanf("%d%d",&N,&M); for(int i=0; i<N; i++) scanf("%s",&field[i]);//不能用scanf("%s",&field[i][j]),scanf会读回车,会乱了 for(int i=0; i<N; i++) { for(int j=0; j<M; j++) if(field[i][j]=='W') { dfs(i,j); sum++; } } printf("%d\n",sum); return 0; }
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