题意:给定你一个迷宫，从起点走到终点，不能走重复的路，一定要在T步的时候走到终点
解题思路：奇偶判断+可到达判断
解题代码：
1 #include <stdlib.h> 2 #include <stdio.h> 3 #include <string.h> 4 #include <math.h> 5 int bex,bey,enx,eny; 6 int xadd[5] = {0,1,0,-1}; 7 int yadd[5] = {1,0,-1,0}; 8 int map[10][10]; 9 int n , m ,limit; 10 int ok = 0; 11 int visit[10][10]; 12 int ABS(int x) 13 { 14 if(x <= 0 ) 15 return -x; 16 else return x; 17 } 18 void dfs(int x, int y , int step) 19 { 20 //printf("%d %d %d %d %d ",x,y,limit - step,ABS(enx-x), ABS(eny -y)); 21 if(map[x][y] == 2 && step == limit) 22 { 23 ok = 1; 24 return ; 25 } 26 27 if(ABS(enx-x) + ABS(eny -y) > limit - step) 28 return; 29 if(ok) 30 return; 31 for(int i = 0 ;i <= 3;i ++) 32 { 33 int tx =x + xadd[i]; 34 int ty =y + yadd[i]; 35 if(map[tx][ty] && !visit[tx][ty]) 36 { 37 visit[tx][ty] = 1; 38 dfs(tx,ty,step+1); 39 visit[tx][ty] = 0; 40 } 41 42 } 43 } 44 int main() 45 { 46 while(scanf("%d %d %d",&n,&m,&limit)!=EOF, n) 47 { 48 memset(map,0,sizeof(map)); 49 memset(visit,0,sizeof(visit)); 50 ok = 0 ; 51 for(int i =1 ;i<= n;i ++) 52 { 53 char str[10]; 54 scanf("%s",&str[1]); 55 for(int j =1;j <= m;j ++) 56 { 57 if(str[j] == 'S') 58 { 59 bex = i; 60 bey = j; 61 map[i][j] = 1 ; 62 } 63 else if(str[j] == 'D') 64 { 65 enx = i ; 66 eny = j ; 67 map[i][j] = 2; 68 }else if(str[j] == '.') 69 map[i][j] = 1; 70 else map[i][j] = 0 ; 71 72 } 73 74 } 75 visit[bex][bey] = 1; 76 // printf("%d %d ",enx,eny); 77 if((limit - (ABS(enx -bex) + ABS(eny-bey))) % 2 != 1 ) 78 dfs(bex,bey,0); 79 if(ok) 80 printf("YES "); 81 else printf("NO "); 82 } 83 84 return 0 ; 85 }