Evaluating postfix and infix expression
So given an expression in postfix form evaluate the expression
The idea is to use stacks to store operands . Whenever we see an operand we push it on stack . When we see an operator we pop out the two values from the operand do the operation and push the result back on the operand
After we run through the array the final result should be at the top of the stack
For Infix we should use two stacks one for operator and the other for operand the key is to do the operation instructed by operator on operands as we run through the array.
We should do the operation indicated by operand as long as we do not find any operator whose precedence is less than the given operator