Distinct Duplicate Values
Problem statement
Given an integer array data, return every distinct value that appears at least twice.
Return each duplicate value exactly once, ordered by the position of its first occurrence in data. If no value is duplicated, return an empty array.
Function
findDuplicateValues(data: int[]) → int[]Examples
Example 1
data = [4,2,4,3,2,4]return = [4,2]Values 4 and 2 both occur more than once. The first 4 appears before the first 2.
Example 2
data = [1,2,3,4]return = []Every value appears exactly once.
Example 3
data = [7,7,7,7]return = [7]The repeated value is returned only once regardless of how many times it appears.
Constraints
1 <= data.length <= 100000.-10^9 <= data[i] <= 10^9.
Source note: Author-written prompt excerpt retained for source fidelity.