Write a function that takes in a ...

Write a function that takes in a string of lowercase English-alphabet letters and returns the index of the string's first non-repeating character. The first non-repeating character is the first character in a string that occurs only once. if the input string doesn't have any non-repeating characters, your function should return -1. Sample Input: string = "abcdcaf" Sample Output: 1 // The first non - repeating character is "b" and is found at index 1.