#### 448. Find All Numbers Disappeared in an Array

Given an array nums of n integers where nums[i] is in the range [1, n], return an array of all the integers in the range [1, n] that do not appear in nums. Example 1: Input: nums = [4,3,2,7,8,2,3,1] Output: [5,6] Example 2: Input: nums = [1,1] Output: [2] Constraints: n == nums.length 1 <= […]

#### Check If N and Its Double Exist

Given an array arr of integers, check if there exist two indices i and j such that: i != j 0 <= i, j < arr.length arr[i] == 2 * arr[j] Example 1: Input: arr = [10,2,5,3] Output: true Explanation: For i = 0 and j = 2, arr[i] == 10 == 2 * 5 […]

#### 3. Longest Substring Without Repeating Characters

Given a string s, find the length of the longest substring without repeating characters. Example 1: Input: s = “abcabcbb” Output: 3 Explanation: The answer is “abc”, with the length of 3. Example 2: Input: s = “bbbbb” Output: 1 Explanation: The answer is “b”, with the length of 1. Example 3: Input: s = […]