HDU 1010 Tempter of the Bone

The problem is a deep search of the typical problem, in time t accurate to reach the end, processing bad either WA or TLE. There are two very important pruning: first, the odd and even pruning, must be in advance to determine the good ' S ' and ' D ' between the Manhattan distance and time t is the same parity, otherwise it will TLE, and the second is to judge '. ' Whether the number is greater than or equal to t-1, this can make the program much faster, but not necessary, I tried to remove it after or can It's just a few more times.

1#include <cstdio>2#include <cstring>3#include <algorithm>4 using namespacestd;5typedefConst int&cintr;6 intN,m,t,ei,ej;7 8InlineintDist (cintr x, cintr y, cintr x2, Cintr y2) {9     returnABS (X-X2) +abs (yy2);Ten } One  A BOOLFlag; - Charmap[Ten][Ten]; - intdir[2][4]= {{-1,0,0,1},{0,-1,1,0}}; the  - voidDfsintIintJintTime ) { -     if(flag)return ; -     if(I==ei && J==ej && time==t) { +flag=true; -         return ; +     } A     inttmp=Dist (I,J,EI,EJ); at     //no more odd-and-even pruning judgment, in the main function has been judged good, here only to make time to judge -     if(Time+tmp > t/*|| (tmp+t-time) &1*/)return ; -      for(intk=0; k<4; ++k) { -Cintr di= i+dir[0][k], dj= j+dir[1][k]; -         CharCh=MAP[DI][DJ]; -         if(map[di][dj]!='X'){ inmap[di][dj]='X'; -DFS (di,dj,time+1); tomap[di][dj]=ch; +         } -     } the } *  $ intMain () {Panax Notoginseng     intI,J,SI,SJ; -      while(~SCANF ("%d%d%d",&n,&m,&t), N) { thememset (Map,'X',sizeof(map)); +flag=false; A         intPoint=0; the GetChar (); +          for(i=1; i<=n; ++I,getchar ()) -              for(j=1; j<=m; ++j) $                 if((map[i][j]= getchar ()) = ='S') si= I, sj=J; $                 Else if(map[i][j]=='D') ei= I, ej=J; -                 Else if(map[i][j]=='.')      ++Point ; -         inttmp=Dist (SI,SJ,EI,EJ); the         //two important pruning, using point to make the first judgment (greatly improving the efficiency), -         //and then the odd-even pruning, just one cut.Wuyi         if(Point < T1|| (tmp+t) &1) { thePuts"NO"); -             Continue; Wu         } -map[si][sj]='X'; AboutDFS (SI,SJ,0); $Puts (flag?)"YES":"NO"); -     } -     return 0; -}

HDU 1010 Tempter of the Bone