zoj 3782 Ternary Calculation

#include<stdio.h>#include<string.h>#include<stack>using namespace std;int main(){    int i,t;    scanf("%d%*c",&t);    int a,b;    char s[250],c;    while(t--)    {        gets(s);        stack<char>s1;        stack<int>s2;        for(i=0; s[i]; i++)        { if(s[i]>='0'&&s[i]<='9') {     a=0;     while(s[i]>='0'&&s[i]<='9')     {         a=a*10+s[i]-'0';         i++;     }     i--;     s2.push(a); } else if(s[i]=='-'||s[i]=='+') {     if(!s1.empty())     {         c=s1.top();         s1.pop();         a=s2.top();         s2.pop();         b=s2.top();         s2.pop();         if(c=='+')  a+=b;         else  a=b-a;         s2.push(a);         s1.push(s[i]);     }     else         s1.push(s[i]); } else if(s[i]=='/' || s[i] == '*' || s[i] == '%') {     char ch = s[i];     b=0;     i+=2;     while(s[i]>='0'&&s[i]<='9')     {         b=b*10+s[i]-'0';         i++;     }     i--;     a=s2.top();     s2.pop();     if(ch == '/')         a=a/b;     else if(ch == '*')         a = a*b;     else if(ch == '%')         a = a%b;     s2.push(a); }        }        while(!s1.empty())        { c=s1.top(); s1.pop(); a=s2.top(); s2.pop(); b=s2.top(); s2.pop(); if(c=='+')     a+=b; else     a=b-a; s2.push(a);        }        printf("%dn",s2.top());    }    return 0;}