#0263

Evaluate Reverse Polish Notation

MediumDSA28 min20 XP

Problem

Given tokens in Reverse Polish Notation, return the integer result. Division should truncate toward zero.

Why This Matters

RPN removes parentheses by making operation order explicit, which is a clean intro to expression parsers.

Function Signature

def eval_rpn(tokens):

Examples

Example 1

Inputtokens = ["2","1","+","3","*"]

Output9

(2 + 1) * 3 equals 9.

Constraints

Return the exact requested value.
Handle edge cases cleanly.
Use the intended DSA pattern when brute force would scale poorly.

CodePython

def eval_rpn(tokens):
    """
    Input example: tokens = ["2","1","+","3","*"]
    Return: 9
    Return the value from the function so the tests can compare it. Do not print unless the prompt asks.
    """
    # write your code here
    return 0

def eval_rpn(tokens):
    """
    Input example: tokens = ["2","1","+","3","*"]
    Return: 9
    Return the value from the function so the tests can compare it. Do not print unless the prompt asks.
    """
    # write your code here
    return 0

Visible browser tests run here when available.

Testcases2 visible / 3 hidden categories

Addition then multiply

Input["2","1","+","3","*"]

Expected9

The + result becomes the left side of multiplication.

Division truncates

Input["4","13","5","/","+"]

Expected6

13 / 5 truncates to 2, then 4 + 2 = 6.

Hidden Test Categories

negative numberssubtraction ordersingle number expression