Decide whether a list of elements contains duplicate values or not.
Input- a list A [left..right] of elements Output- return true if there exists two elements. A[i], A[j],
i !=j in list A such that A[i] == A[j]; return false if all elements in list A are unique. Assumption: the
type of list element supports comparison operations such as ==, <...
Example: A[0...8]= {1,-30,20,3,20, -3, -2,18, -30,5) Output: true (as A[2]) == A[4])