Evaluation of postfix expression
An expression is called the postfix expression if the operator appears in the expression after the operands.
Example :
Infix expression: A + B * C - D
Postfix expression: A B + C D - *
Given a postfix expression, the task is to evaluate the expression. The answer could be very large, output your answer modulo (10^9+7). Also, use modular division when required.
Note:
1. Operators will only include the basic arithmetic operators like '*', '/', '+', and '-'.
2. The operand can contain multiple digits.
3. The operators and operands will have space as a separator between them.
4. There won’t be any brackets in the postfix expression.
Input format:
The first line of input contains an integer ‘T’ denoting the number of test cases.
The next ‘T’ lines represent the ‘T’ test cases.
The first and only line of each test case contains a postfix expression.
Output format
For each test case, print an integer obtained by evaluating the given postfix expression.
Note:
You are not required to print the expected output; it has already been taken care of, Just implement the function.
Constraints
1 <= T <= 100
1 <= N <= 10^3
1 <= NUM <= 100
Where ‘N’ denotes the length of postfix expression and ‘NUM’ denotes the operand.
Time Limit: 1 sec
CodingNinjas
author
2y
Create a stack to store operands
Scan the given expression
-> If the element is a number, push it into the stack
-> If the element is an operator, pop operands for the operator from the stack. Evaluate t...read more
CodingNinjas
author
2y
Evaluation of postfix expression.
The idea is to use a stack to store the operands. Whenever an operator is encountered, we pop the top two numbers from the stack, perform the operation and push the r...read more
Help your peers!
Add answer anonymously...
Top Amazon Software Developer interview questions & answers
Popular interview questions of Software Developer
Top HR questions asked in Amazon Software Developer
Stay ahead in your career. Get AmbitionBox app
Helping over 1 Crore job seekers every month in choosing their right fit company
65 L+
Reviews
4 L+
Interviews
4 Cr+
Salaries
1 Cr+
Users/Month
Contribute to help millions
Get AmbitionBox app