Given an integer array nums, return true if any value appears at least twice in the array, and return false if every element is distinct.

Example 1:
Input: nums = [1,2,3,1]
Output: true

Example 2:
Input: nums = [1,2,3,4]
Output: false

Example 3:
Input: nums = [1,1,1,3,3,4,3,2,4,2]
Output: true

Constraints:

1 <= nums.length <= 105
-109 <= nums[i] <= 109

Solution:

class Solution {
    public boolean containsDuplicate(int[] no) {
         if(no==null || no.length==0)
        return false;

    HashSet<Integer> set = new HashSet<Integer>();
    for(int i: no){
        if(!set.add(i)){
            return true;
        }
    }

    return false;

    }
}

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