In 91

上回邀請朋友一起來進行 pair programming，隨機挑了一個 Codewars 的題目來練習：Mumbling。

題目描述：

LeetCode 58: Length of Last Word

Codewars 上隨機挑到的題目：Number of People in the Bus

Leet Code 題目 121: Best Time to Buy and Sell Stock

Codewars 上隨機挑到的一個題目：Buying A Car

LeetCode 136 題：Single Number

LeetCode 第 15 題: 3 Sum。

LeetCode 第三題 "Longest Substring Without Repeating Characters" 

LeetCode 第 231 題："Power of Two"，相當單純的題目。

Given an integer, write a function to determine if it is a power of two.

LeetCode 第九題 Palindrome Number ，判斷一個數字是否為「回文」。

Determine whether an integer is a palindrome. Do this without extra space. 

 LeetCode 的第 1 題 "Two Sum"，題目描述如下。

用 TDD 來練習完成 LeetCode 的第 2 題，題目描述如下。

LeetCode 326: Power of Three

Given an integer, write a function to determine if it is a power of three.

Follow up:
Could you do it without using any loop / recursion?

用 TDD 來練習完成 leet code 的第 220 題，題目描述如下。

Given an array of integers, find out whether there are two distinct indices i and j in the array such that the absolute difference between nums[i] and nums[j] is at most t and the absolute difference between i and j is at most k.

Codewars 上的 kata: Next bigger number with the same digits

You have to create a function that takes a positive integer number and returns the next bigger number formed by the same digits:
f(12) == 21
f(513) == 531
f(2017) == 2071

If no bigger number can be composed using those digits, return -1:
f(9) == -1
f(111) == -1
f(531) == -1

用 TDD 來練習完成 leet code 的第 219 題，題目描述如下。

Given an array of integers and an integer k, find out whether there are two distinct indices i and j in the array such that nums[i] = nums[j] and the absolute difference between i and j is at most k.