E- Seven tombs 表达式运算 + DFS

算法：

1.表达式运算

2.DFS枚举

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<iostream>
#include<vector>
#include<string>
#include<math.h>
#include<map>
#include<set>
#include<stack>
#include<algorithm>
using namespace std;
stack<int>OpE;//操作数栈 
stack<char>OpR;//运算符栈 
//算符间优先级 
int Opet[100], hash[100], len1,len2;
bool vis;
int visit[100];
char str[1000];
char temp[110];
//栈顶优先权 
int Pri[8][8] = {{1,1,-1,-1,-1,1,1},
                 {1,1,-1,-1,-1,1,1},
                 {1,1,1,1,-1,1,1},
                 {1,1,1,1,-1,1,1},
                 {-1,-1,-1,-1,-1,0,0},
                 {1,1,1,1,1,1,1},
                 {-1,-1,-1,-1,-1,-1,-2}
                };
void init( )
{
  memset(Opet,0,sizeof(Opet));
  Opet['+'] = 0,Opet['-'] = 1,Opet['*'] = 2;
  Opet['/'] = 3,Opet['('] = 4, Opet[')'] = 5;
  Opet['#'] = 6;    
}
//判断优先级 
int jugde( char p, char q)
{
   return Pri[Opet[p]][Opet[q]];    
}

int solve(char *str2)
{
  char str1[120];
  strcpy(str1,str2);
  int len = strlen(str1), x, y, i = 0, j;
  char Op = 0, tp[110];
  while( !OpE.empty( ) )
         OpE.pop();
  while( !OpR.empty() )
         OpR.pop();
  OpR.push('#');
  bool f = true;
  str1[len] = '#';
  while( i <= len && f)
  {  
     if( str1[i] >= 'A' && str1[i] <= 'G' ) //操作数直接入栈 
     {  
          int ans = 0;
          for(j = i; j < len; j++)
             if( str1[j] >= 'A' && str1[j] <= 'G' )
               tp[ans++] = hash[str1[j]] + '0';
             else
               break;
          i = j;
          tp[ans] = '\0';
          OpE.push(atoi(tp));
     }
     else
     {  
        switch( jugde(OpR.top(),str1[i]) )
        {
          case 0: OpR.pop();i++;break; 
          case 1: 
          {
             Op = OpR.top( );
             OpR.pop();
             x = OpE.top();
             OpE.pop();                 
             y = OpE.top( );
             OpE.pop( ); 
             if( Op == '+' )
                 OpE.push( x + y );
             else if( Op == '-' )
                 OpE.push( y - x );
             else if( Op == '*' )
                 OpE.push( y * x );
             else if( Op == '/' )
                 OpE.push( y / x );
             break;    
          }
          case -1: OpR.push(str1[i]);i++;break;
          case -2: f = false;break;    
        }    
         
     }    
       
  }
  return OpE.top();
}

void DFS(int num)
{
   if( vis )
       return;
   if( num == 7 )
   {  
      int x = solve(str);
      int y =  solve(temp);
      if( x == y)
      {
          vis = true;
          for( int i = 0; i < len1; i++)
              if( str[i] >= 'A' && str[i] <= 'G' )
                 printf("%d",hash[str[i]]);
              else
                 printf("%c",str[i]);
          printf("=");
          for( int i = 0; i < len2; i++)
             if( temp[i] >= 'A' && temp[i] <= 'G' )
                    printf("%d",hash[temp[i]]);
             else
                  printf("%c",temp[i]);  
          puts("");
      }
      return;
   }     
   for( int i = 1; i <= 7; i++)
   {
     if( !visit[i] )
     {
        visit[i] = 1;
        hash[num+'A'] = i;
        DFS(num + 1);
        visit[i] = 0;   
        if( vis )
          return;
     }
   
   }  
}
 
int main( )
{
   init( );
   while( scanf("%s",str) != EOF )
   { 
     vis = false;
     memset(visit,0,sizeof(visit));
     memset(hash,0,sizeof(hash));
     char *p = strtok(str,"=");
     strcpy(str,p);
     p = strtok(NULL,"=");
     strcpy(temp,p);
     len1 = strlen(str);
     len2 = strlen(temp);
     DFS(0);
   }
   return 0;
}