Given a string s and an integer k, return the length of the longest substring of s such that the frequency of each character in this substring is greater than or equal to k. If no such substring exists, return 0.
Given an integer array nums with potential duplicates, you need to randomly select an index i where nums[i] == target. If there are multiple indices with the same value, the selection should be made with equal probability for each valid index.
Given a string consisting of lowercase and/or uppercase English letters, find the length of the longest palindrome that can be constructed from the letters in the string. Letters are case-sensitive.
Given an array of integers, your task is to find the maximum result of the XOR operation between any two elements from the array. The goal is to maximize the XOR value of any pair of numbers in the array, where the XOR of two numbers is computed using the bitwise XOR operation.
You are given a string representing an out-of-order English representation of digits from 0 to 9. Your task is to rearrange the characters of the string in such a way that you can extract the digits in ascending order. The string will only contain valid letters corresponding to the English representations of digits.
You are given a string s consisting of uppercase English letters and an integer k. You can change any character in the string to any other uppercase English character, but you are allowed to perform this operation at most k times. The goal is to find the length of the longest substring that contains the same letter after performing at most k character changes.
