Problem Statement

Write a function solution that, given a string S of length N , returns the length of the shortest unique substring of S , that is, the length of the shortest word which occurs in S exactly once. Examples: Given S = "abaaba" , the function should return 2 . The shortest unique substring of S is "aa" . Given S = "zyzyzyz" , the function should return 5 . The shortest unique substring of S is "yzyzy" . Note that there are shorter words, like "yzy" , occurrences of which overlap, but they still count as multiple occurrences. Given S = "aabbbabaaa" , the function should return 3 . All substrings of size 2 occur in S at least twice. Assume that: N is an integer within the range [1..200] ; string S is made only of lowercase letters ( a - z ). In your solution, focus on correctness. The performance of your solution will not be the focus of the assessment.