Solve common string and subarray problems

Implement three independent functions. For the first function, you are given a string s and must return a new string whose characters are the characters of s written from last to first. For the second function, you are given an integer array nums that can include negative values. Return the largest sum obtainable from any contiguous block containing one or more elements. For the third function, you are given an integer array nums that can include negative values and zeros.…