pat02-linear structure 3. Find the value of the prefix expression (25)

02-Linear Structure 3. To find the value of the prefix expression (25) time limit MS Memory limit 65536 KB code length limit 8000 B award Program Standard

The arithmetic expression has the form of prefix notation, infix notation and suffix notation. The prefix expression means that the two-tuple operator precedes two operands, such as the prefix expression for 2+3* (7-4) +8/4: + + 2 * 3-7 4/8 4. Please design the program to calculate the result value of the prefix expression.

Input Format Description:

Enter a prefix expression of no more than 30 characters in a row, containing only the + 、-、 *, \, and operands, separated by a space between the different objects (operands, operation symbols).

Output Format Description:

The output prefix expression evaluates to 1 digits after the decimal point, or error message "error".

Sample input and output:

Serial number	Input	Output
1	+ + 2 * 3-7 4/8 4	13.0
2	/-25 + *-2 3 4/8 4	12.5
3	/5 + *-2 3 4/8 2	ERROR
4	+10.23	10.2

Submit Code

1#include <cstdio>2#include <algorithm>3#include <iostream>4#include <cstring>5#include <queue>6#include <vector>7#include <string>8#include <stack>9 using namespacestd;Ten intMain () { One     //freopen ("D:\\input.txt", "R", stdin); Astack<Double>fi; -stack<string>input; -     strings; the      -     //bool Can=true; -      while(cin>>s) { - Input.push (s); +     } -      while(!Input.empty ()) { +s=input.top (); A Input.pop (); at         if(s.length () = =1&&! (s[0]>='0'&&s[0]<='9')){ -             DoubleA=fi.top (); - Fi.pop (); -             Doubleb=fi.top (); - Fi.pop (); -             Switch(s[0]){ in                  Case'+':{ -                     //cout<< "+:" <<a+b<<endl; toFi.push (A +b); +                      Break; -                 } the                  Case'-':{ *                     //cout<< "-:" <<a-b<<endl; $Fi.push (A-b);Panax Notoginseng                      Break; -                 } the                  Case'*':{ +                     //cout<< "*:" <<a*b<<endl; AFi.push (A *b); the                      Break; +                 } -                  Case'/':{ $                     if(b==0){ $printf"error\n"); -                         //Can=false; -                         return 0; the                     } -                     //cout<< "/:" <<a/b<<endl;WuyiFi.push (A/b); the                      Break; -                 } Wu                 default:{ -printf"error\n"); About                         return 0; $                 } -             } -}Else if((s[0]>='0'&&s[0]<='9')|| (S.length () >1&&! (s[0]>='0'&&s[0]<='9') && (s[1]>='0'&&s[1]<='9'))){ -             DoubleCal=1; A             intI=0; +             if(s[i]=='+'|| s[i]=='-'){ the                 if(s[i]=='-'){ -cal=-1; $                 } thei++; the             } the             Doubleintpart=0, decpart=0; the              while(I<s.length () &&s[i]!='.'){//Note Conversion -intpart*=Ten; inintpart+=s[i++]-'0'; the             } thei++; About             intJ; the              for(J=s.length ()-1; j>=i;j--){ thedecpart+=s[j]-'0'; thedecpart*=0.1; +             } -Fi.push (cal* (intpart+decpart)); the}Else{Bayiprintf"error\n"); the             return 0; the         }     -     } -     //cout<<fi.top () <<endl; the      theprintf"%.1lf\n", Fi.top ()); the     return 0; the}

pat02-linear structure 3. Find the value of the prefix expression (25)