Integer to English Words (https://leetcode.com/problems/integer-to-english-words/)

Convert a non-negative integer to its english words representation. Given input is guaranteed to be less than 231 - 1.

Example 1:

Input: 123 Output: "One Hundred Twenty Three" Example 2:

Input: 12345 Output: "Twelve Thousand Three Hundred Forty Five" Example 3:

Input: 1234567 Output: "One Million Two Hundred Thirty Four Thousand Five Hundred Sixty Seven" Example 4:

Input: 1234567891 Output: "One Billion Two Hundred Thirty Four Million Five Hundred Sixty Seven Thousand Eight Hundred Ninety One"

Basic Calculator || (https://leetcode.com/problems/basic-calculator-ii/)

Implement a basic calculator to evaluate a simple expression string.

The expression string contains only non-negative integers, +, -, *, / operators and empty spaces . The integer division should truncate toward zero.

Example 1:

Input: "3+2*2" Output: 7 Example 2:

Input: " 3/2 " Output: 1 Example 3:

Input: " 3+5 / 2 " Output: 5 Note:

You may assume that the given expression is always valid. Do not use the eval built-in library function.