c programming seashell

implement the three functions and functions must meet the time efficiency requirements

// max_diff (a, len) finds the maximum difference between two elements in a // time: O (n) int max_diff (const int all, int len); // select (a, len) finds the kth smallest value out of of a (starting from 0, 11 e.g. k-0 selects the smallest, k-len-1 selects the largest) // requires: a is a valid array with len elements all elements of a are distinct 0