多校联合第4场： ZZ的计算器

题意：模拟运算

解题思路：表达式数构建   模拟（ztw同学的算法）

解题代码

// File Name: 表达式树.c
// Author: darkdream
// Created Time: 2013年04月18日 星期四 19时37分36秒

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<time.h>
#include<math.h>
int num[50];
const int maxn = 1000;
int lch[maxn] , rch[maxn];
char op[maxn];
int nc = 0;
int ok = 1;
int build_tree(char *s,int x,int y)
{   
    //printf("%d****%d\n",x,y);
    int i , c1 =-1, c2 = -1, p =0;
    int u ;
    if(y - x == 1)
    {
      u = ++nc;
      lch[u] = rch[u] = 0 ;
      op[u] = s[x];
      return u ;
    }
    for(int i = x; i < y ; i++)
    { 
       switch(s[i])
       {
         case '(' :p++;break;
         case ')' :p--;break;
         case '+':case '-':if(!p) c1 = i ; break;
         case '*':case '/':if(!p) c2 = i ;break;
       }
    }
    if(c1 < 0) c1 = c2;
    if(c1 < 0) return build_tree(s,x+1,y-1);
    u = ++nc;
    lch[u] = build_tree(s,x,c1);
    rch[u] = build_tree(s,c1+1,y);
    op[u] = s[c1];
    return u ;
}
long long  find(int i)
{  
    if(lch[i] == 0)
    {
        return num[op[i]-'a'];
    }
   if (op[i] == '+')
       return find(lch[i])+find(rch[i]);
   if (op[i] == '-')
       return find(lch[i])-find(rch[i]);
   if (op[i] == '*')
       return find(lch[i])*find(rch[i]);
   if (op[i] == '/')
   {
       if(find(rch[i]) == 0)
       {
        ok = 0;
        return find(lch[i])/1;

       }
       else
          return find(lch[i])/find(rch[i]);
   }
}
int main(){

   //freopen("/home/plac/problem/input.txt","r",stdin);
   //freopen("/home/plac/problem/output.txt","w",stdout);
   char s[1000];
   while(scanf("%s",s) != EOF)
   {
     memset(lch,0,sizeof(lch));
     memset(rch,0,sizeof(lch));
     memset(op,0,sizeof(op));
     memset(num,0,sizeof(num));
     nc = 0; 
     ok = 1;
     char c = 'a';
      char str[56] ={0};
      int k = -1;
      int temp = 0;
      for(int i = 0;i < strlen(s);i ++)
      {
         if(s[i] <= '9' && s[i] >= '0')
         {
           temp = temp*10 +(s[i]-'0');
         }
         else
         {
            str[++k] = c;
            num[c-'a'] = temp;
            c++;
            str[++k] = s[i];
            temp = 0;
         }
         if(i == strlen(s)-1)
         {
           str[++k] = c;
           num[c-'a'] = temp;
        
         }
      }
     
     
     build_tree(str,0,strlen(str));
     int ans = find(1);
     if(!ok)
         printf("impossible\n");
     else
       printf("%lld\n",find(1));
   }
return 0 ;
}

#include<stdio.h>
#include<string.h>
#define LL long long

int main()
{
    LL d[10000] , temp , count;
    LL i , j;
    char ch[200];
    while(gets(ch))
    {
        count=temp=0;
        for(j=0 ; j<strlen(ch) ; j++)
        {
            if(ch[j]>='0'&&ch[j]<='9')
                temp = temp*10+ch[j]-'0';
            else
                break;
        }
        d[count++]=temp;
        for(i=j ; i<strlen(ch) ; i++)
        {
            temp=0;
            for(j=i+1 ; ch[j]>='0'&&ch[j]<='9' ; j++)
                temp = temp*10+ch[j]-'0';
            if(ch[i]=='*')
                d[count-1] *= temp;
            else if(ch[i]=='/')
                d[count-1] /= temp;
            else 
                if(ch[i]=='+')
                    d[count++] = temp;
                else
                    d[count++] = (-1)*temp;
                i=j-1;
            }
            for(i=1 ; i<count ; i++)
                d[0]+=d[i];
            printf("%lld\n",d[0]);
        }
    return 0;
}