LeetCode in Swift: Evaluate Reverse Polish Notation

Problem Statement

Evaluate the value of an arithmetic expression in Reverse Polish Notation.

Valid operators are +, -, *, /. Each operand may be an integer or another expression.

Some examples:

Original LeetCode problem page

My Solution in Swift

A simple stack can be used to solve the problem in linear time O(n)

Try It Yourself

1: each links to a blog post of mine that is dedicated to the problem
2: total execution time of a solution on my MacBook Pro (Late 2013, 2.6 GHz Intel Core i7, 16 GB 1600 MHz DDR3). Each solution is compiled with following command:

$ swiftc -O -sdk `xcrun --show-sdk-path --sdk macosx` json.swift main.swift -o mySolution

The total execution time is the average of 10 runs.
3: these test cases are semi-automatically :P retrieved from LeetCode Online Judge system and are kept in JSON format
4: each Xcode project includes everything (my Swift solution to a problem, its JSON test cases and a driver code to test the solution on those test cases)

Problem1Time2Test Cases3My Xcode Project4
Evaluate Reverse Polish Notation107.186ms Save  (1767) Save  (1665)

More Problems Solved in Swift

My full list of LeetCode problems attempted using Swift