HDU 1072 (BFS) has a bomb

http://acm.hdu.edu.cn/showproblem.php?pid=1072

The main idea is on a NXM map, 0 means the wall, 1 for the Open space, 2 for the person, 3 for the destination, and 4 for the time bomb reboot.

Time bombs are 6, and the time required to take one step is 1. You can move up, down, left, and right one cell at a time.

When the person goes to 4 o'clock if the bomb time is not 0, you can reset the bomb time to 6. If a man goes to 3 and the bomb is not 0 o'clock,

Success out. Begging for the shortest time from 2 to 3.

A typical search, using the BFS, the structure of a step to indicate the time required, it is equivalent to the number of steps, a time to represent the bomb,

Note that here in fact each point can be repeated access, in order to reach the minimum time, 4 of the location if you have to go, actually only walk once

A bomb point if go many times, although set the maximum time limit but the round-trip consumption is not worth the candle, think about here

Code

1#include <cstdio>2#include <queue>3#include <cstring>4 using namespacestd;5 structPoint {6     intx, y;7     inttime,step;//bomb time and number of steps8 };9 intdx[]={1,-1,0,0};Ten intdy[]={0,0,1,-1}; One intn,m; A intvisit[Ten][Ten],map[Ten][Ten]; - intBFsintSxintSy) - { the     inti; -memset (Visit,0,sizeof(visit)); -Queue<point>Q; - Point now,next; +now.x=sx;now.y=Sy; -Now.time=6; +now.step=0; Avisit[now.x][now.y]=1; at Q.push (now); -      while(!q.empty ()) -     { -now=Q.front (); - Q.pop (); -         if(map[now.x][now.y]==3) in             returnNow.step; -         if(now.time<=1)Continue; to          for(i=0;i<4; i++) +         { -next.x=now.x+Dx[i]; thenext.y=now.y+Dy[i]; *             if(next.x<1|| next.x>n| | next.y<1|| NEXT.Y&GT;M)Continue; $             if(map[next.x][next.y]==0)Continue;Panax Notoginseng             if(visit[next.x][next.y]==1)Continue; -next.step=now.step+1; thenext.time=now.time-1; +             if(map[next.x][next.y]==4) A             { theNext.time=6; +visit[next.x][next.y]=1;//Make sure to go only once, Mark -             } $ Q.push (next); $         } -     } -     return-1; the } - intMain ()Wuyi { the     intT,i,j,sx,sy; -      while(~SCANF ("%d",&t)) { Wu      while(t--) -     { Aboutscanf"%d%d",&n,&m); $          for(i=1; i<=n;i++) -         { -              for(j=1; j<=m;j++) -             { Ascanf"%d",&map[i][j]); +                 if(map[i][j]==2) the                 { -sx=i; $sy=J; the                 } the             } the         } theprintf"%d\n", BFS (Sx,sy)); -     } in     } the     return 0; the}

HDU 1072 (BFS) has a bomb