Given an array of integers, find if the array contains any duplicates.
Your function should return true if any value appears at least twice in the array, and it should return false if every element is distinct.
Input: [1,2,3,1]
Output: true
Input: [1,2,3,4]
Output: false
Input: [1,1,1,3,3,4,3,2,4,2]
Output: true
Solutions (Click to expand)
We can use a set to insert numbers as we iterate over the array. If the number we want to add to the set is already in the array, then it is a duplicate.
Time: O(N)
Space: O(N)