Design a HashMap without using any built-in hash table libraries.

Implement strStr().

Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.

Given an array nums and a value val, remove all instances of that value in-place and return the new length.

Given an array nums containing n distinct numbers in the range [0, n], return the only number in the range that is missing from the array.

You have a set of integers s, which originally contains all the numbers from 1 to n. Unfortunately, due to some error, one of the numbers in s got duplicated to another number in the set, which results in repetition of one number and loss of another number.

Alice has n candies, where the ith candy is of type candyType[i]. Alice noticed that she started to gain weight, so she visited a doctor.

Given a sorted array nums, remove the duplicates in-place such that each element appears only once and returns the new length.

Write a function to find the longest common prefix string amongst an array of strings.