1. Longest Subarray With Limited Difference Problem Given an integer array nums and an integer k, find the length of the longest contiguous subarray such that the absolute difference between the maximum and minimum elements in the subarray is less than or equal to k. 2. Decode String Problem Given an encoded string, return its decoded version. The encoding rule is: k[encoded_string] The string inside the brackets must be repeated k times. 3. 3Sum Problem Given an integer array nums, return all unique triplets [nums[i], nums[j], nums[k]] such that: i ≠ j ≠ k nums[i] + nums[j] + nums[k] = 0 4. Valid Parentheses Problem Given a string containing only: ( ) { } [ ] Determine if the string is valid. A string is valid if: Open brackets are closed by the same type Open brackets are closed in the correct order 5. Longest Substring Without Repeating Characters Problem Given a string s, find the length of the longest substring without repeating characters. 6. Group Anagrams Problem Given an array of strings, group anagrams together. Two strings are anagrams if they contain the same characters in a different order. 7. Task Scheduler Problem You are given CPU tasks represented by letters A–Z and a cooling period n. The same task cannot run again until n intervals pass. 8. Minimum Window Substring Problem Given two strings s and t, find the smallest substring in s that contains all characters of t. If no such substring exists, return empty string. Return the minimum number of CPU intervals required to finish all tasks.