217. Contains Duplicate

217. Contains Duplicate

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

My Solutions:

方法1：用set，保证element唯一性

方法2：先sort，再看element是不是和前一个相同

public class Solution {
    public boolean containsDuplicate(int[] nums) {
        
        //Method 1
        // Set<Integer> set = new HashSet<>();
        // for (int i : nums) {
        //     if (set.contains(i)) return true;
        //     set.add(i);
        // }
        // return false;
        
        
        //Method 2
        Arrays.sort(nums);
        for(int ind = 1; ind < nums.length; ind++) {
            if(nums[ind] == nums[ind - 1]) {
                return true;
            }
        }
        return false;
    }
}