ContainsDuplicate.java

// Contains Duplicate - https://leetcode.com/problems/contains-duplicate/description/
// 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

package Questions.Easy;

import java.util.Arrays;
import java.util.HashMap;

public class ContainsDuplicate {

    // approch 1 - TC O(nlogn) , SC O(1)
    static boolean containsDup1(int[] nums) {
        Arrays.sort(nums);

        for (int i = 0; i < nums.length - 1; i++) {
            if (nums[i] == nums[i + 1]) {
                return true;
            }
        }

        return false;
    }
    
    // apprch 2 - TC O(n) , SC O(n)
    static boolean containsDup2(int[] nums) {
        HashMap<Integer,Integer> map = new HashMap<>();
        for (int i = 0; i < nums.length; i++) {
            if (map.containsKey(nums[i])) {
                return true;
            }
            map.put(nums[i],1);
        }
        return false;
    }
}