You are given a list of equations and their corresponding values, where each equation represents a division between two variables. Your task is to determine the result of several queries asking for the division result of two given variables.
Given a string num representing a non-negative integer and an integer k, remove k digits from num such that the remaining number is the smallest possible integer.
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 two non-negative integers represented as strings, return the sum of these numbers as a string. The solution should avoid converting the strings to integers directly or using any built-in libraries for large integers.
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.
