#include <iostream>
#include <cstdlib>
#include <cstring>
#include <cstdio>
#define size 400
using namespace std;
char infix[size],postfix[size],Stack[size];
int top;
int precedence(char ch)
{
switch(ch)
{
case '^':return 5;
case '/':return 4;
case '*':return 4;
case '+':return 3;
case '-':return 3;
default:return 0;
}
}
char Pop()
{
char ret;
if(top!=-1)
{
ret=Stack[top];
top--;
return ret;
}
else return '#';
}
char Topelem()
{
char ch;
if(top!=-1) ch=Stack[top];
else ch='#';
return ch;
}
char Push(char ch)
{
if(top!=size-1)
{
top++;
Stack[top]=ch;
}
}
int braces(char* s)
{
int l,r;
l=0;r=0;
for(int i=0;s[i];i++)
{
if(s[i]='(') l++;
if(s[i]=')') r++;
}
if(l==r) return 0;
else if(l<r) return 1;
else return -1;
}
int main()
{
char ele,elem,st[2];
int T,prep,pre,popped,j=0,chk=0;
cin>>T;
while(T--)
{
j=0;chk=0;top=-1;
strcpy(postfix," ");
cin>>infix;
chk=braces(infix);
if(chk==0)
{
for(int i=0;infix[i];i++)
{
if(infix[i]=='(')
{
elem=infix[i];
Push(elem);
}
else if(infix[i]==')')
{
while((popped=Pop())!='(')
{
postfix[j++]=popped;
}
}
else if(infix[i]=='^'||infix[i]=='/'||infix[i]=='*'||infix[i]=='+'||infix[i]=='-')
{
elem=infix[i];
pre=precedence(elem);
ele=Topelem();
prep=precedence(ele);
if(pre>prep) Push(elem);
else
{
while(prep>=pre)
{
if(ele=='#') break;
popped=Pop();
ele=Topelem();
postfix[j++]=popped;
prep=precedence(ele);
}
Push(elem);
}
}
}
while((popped=Pop())!='#') postfix[j++]=popped;
postfix[j]='\0';
cout<<postfix;
}
}
}
The Code isn't working. Please Help!
