Problem: A strobogrammatic number is a number that looks the same when rotated 180 degrees (looked at upside down). Write a function to determine if a number is strobogrammatic. The number is represented as a string. For example, the numbers "69"…

Problem: Given a string, find the length of the longest substring T that contains at most 2 distinct characters. For example, Given s = “eceba”, T is "ece" which its length is 3. Analysis: This is a very very typical question in using slide wind…

Given a sorted integer array where the range of elements are in the inclusive range [lower, upper], return its missing ranges. For example, given [0, 1, 3, 50, 75], lower = 0 and upper = 99, return ["2", "4->49", "51->74&quo…

Problem: Given a sorted integer array where the range of elements are [lower, upper] inclusive, return its missing ranges. For example, given [0, 1, 3, 50, 75], lower = 0 and upper = 99, return ["2", "4->49", "51->74",…

Given a sorted integer array nums, where the range of elements are in the inclusive range [lower, upper], return its missing ranges. Example: Input: nums = [0, 1, 3, 50, 75], lower = 0 and upper = 99, Output: ["2", "4->49", "51…

Given a sorted integer array nums, where the range of elements are in the inclusive range [lower, upper], return its missing ranges. Example: Input: nums = [0, 1, 3, 50, 75], lower = 0 and upper = 99,Output: ["2", "4->49", "51-…

Given a sorted integer array where the range of elements are in the inclusive range [lower, upper], return its missing ranges. For example, given [0, 1, 3, 50, 75], lower = 0 and upper = 99, return ["2", "4->49", "51->74&quo…

Missing Ranges Given a sorted integer array where the range of elements are [lower, upper] inclusive, return its missing ranges. For example, given [0, 1, 3, 50, 75], lower = 0 and upper = 99, return ["2", "4->49", "51->74&q…

Given a sorted integer array without duplicates, return the summary of its ranges. Example 1: Input: [0,1,2,4,5,7] Output: ["0->2","4->5","7"] Explanation: 0,1,2 form a continuous range; 4,5 form a continuous range. Exa…

A strobogrammatic number is a number that looks the same when rotated 180 degrees (looked at upside down). Write a function to determine if a number is strobogrammatic. The number is represented as a string. For example, the numbers "69", "…