LeetCode - Contains Duplicate Java - The Coding Shala

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LeetCode Contains Duplicate Problem

In this post, you will learn how to check if an array contains duplicate values in Java.

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.
Example 1:
Input: [1,2,3,1]

Output: true

Example 2:

Input: [1,2,3,4]
Output: false

Example 3:
Input: [1,1,1,3,3,4,3,2,4,2]
Output: true
Practice on LeetCode - Click Here

Contains Duplicate Java Solution

Approach:
We can sort the array and check with the next element but this approach will take O(n logn) time. We can do using HashSet within O(n) time. 
Java Program: 

class Solution {
    public boolean containsDuplicate(int[] nums) {
        Set<Integer> set = new HashSet<Integer>();
        for(int i = 0; i<nums.length; i++){
            int val = nums[i];
            if(set.contains(val)) return true;
            set.add(val);
        }
        return false;
    }
}


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