LeetCode 217. Contains Duplicate Java Solution

Problem

Problem Link

Time Complexity: O(n), Space Complexity: O(n)

class Solution {
    public boolean containsDuplicate(int[] nums) {
        // Create a HashMap to store the elements of the array.
        HashMap<Integer, Integer> map = new HashMap<>();

        // Traverse all elements in the array.
        for (int temp : nums) {
            // Check if the current element exists in the HashMap.
            if (map.containsKey(temp)) {
                // If it exists, it means there is a duplicate element in the array, so return true.
                return true;
            } else {
                // If it doesn't exist, add the current element to the HashMap.
                // The value '1' is used to indicate the existence of a duplicate element.
                map.put(temp, 1);
            }
        }
        // If there are no duplicate elements, return false.
        return false;
    }
}

Explanation

• HashSet internally uses HashMap. Therefore, you can achieve the same result using HashSet.