搜索：zoj 1047 || poj 1111 Image Perimeters—FS）

【转】http://blog.csdn.net/zxy_snow/article/details/5947376

/* * */#include<stdio.h>#include <stdlib.h>#include <iostream>#include <memory.h>using namespace std;int fi,fj,len;int map[25][25],visit[25][25];int dir[16] = {0,1,0,-1,1,0,-1,0,1,1,1,-1,-1,1,-1,-1};int m,n;void DFS(int i,int j){for(int k=0; k<16; k+=2){int a = i+dir[k];int b = j+dir[k+1];if( a>=1 && a<=m && b>=1 && b<=n && !visit[a][b] && map[a][b] ){visit[a][b] = 1;DFS(a,b);}}}int main(void){char str[25];    while( cin >> m >> n >> fi >> fj && m )    {memset(visit,0,sizeof(visit));memset(map,0,sizeof(map));len = 0;for(int i=1; i<=m; i++){cin >> str;for(int k=0; k<n; k++)map[i][k+1] = (str[k] == 'X'? 1 : 0 );}visit[fi][fj] = 1;DFS(fi,fj);for(int i=1; i<=m; i++)for(int j=1; j<=n; j++){if( visit[i][j] )for( int k=0; k<8; k+=2){int a = i+dir[k];int b = j+dir[k+1];if( map[a][b] == 0 ){len++;}}}cout << len << endl;}    return 0;}

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