Given a non-empty array of unsorted integers nums, every element in nums appears twice except for one. Find that single number.

Given a input string text, use the characters of text to form as many instances of the word "balloon" as possible. You are only allowed to

Given an integer array nums, where nums[i] is in the range nums[1,n], return all the missing numbers in the range [1,n] that do not

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

Given an array of integers nums, write an algorithm that returns true if any value appears at least twice in the array, and return false if

Given an integer array nums sorted in ascending order, move all single occurrences of elements in it to the beginning of the nums array