Java repeated letter check in string

Question

I\'m having problem figuring out how to check from users input letters that were repeated. Program needs to output repeated letter as true and if there isn\'t any then as false.

Answer 1

1.) Sort the character array.

2.) Iterate through the array to see if ith value == (i+1)th value. If any found, return false. Else, return true.

Time complexity: O(nlogn) (for sorting)

Space complexity: O(1)