Introduction

In this blog post, we'll share the most commonly asked coding interview questions at Apollo.io. If you don't have months to study for your interviews, you can use AI tools like Chatmagic to generate solutions quickly and efficiently - helping you pass the interviews and get the job offer!

Problem #1: Evaluate Reverse Polish Notation

You are given an array of strings tokens that represents an arithmetic expression in a Reverse Polish Notation. Evaluate the expression. Return an integer that represents the value of the expression. Note that: The valid operators are '+', '-', '', and '/'. Each operand may be an integer or another expression. The division between two integers always truncates toward zero. There will not be any division by zero. The input represents a valid arithmetic expression in a reverse polish notation. The answer and all the intermediate calculations can be represented in a 32-bit integer. Example 1: Input: tokens = ["2","1","+","3",""] Output: 9 Explanation: ((2 + 1) 3) = 9 Example 2: Input: tokens = ["4","13","5","/","+"] Output: 6 Explanation: (4 + (13 / 5)) = 6 Example 3: Input: tokens = ["10","6","9","3","+","-11","","/","","17","+","5","+"] Output: 22 Explanation: ((10 (6 / ((9 + 3) -11))) + 17) + 5 = ((10 (6 / (12 -11))) + 17) + 5 = ((10 (6 / -132)) + 17) + 5 = ((10 0) + 17) + 5 = (0 + 17) + 5 = 17 + 5 = 22 Constraints: 1 <= tokens.length <= 104 tokens[i] is either an operator: "+", "-", "", or "/", or an integer in the range [-200, 200].

Topics: Array, Math, Stack