[刷题防痴呆] 0217 - 存在重复元素 (Contains

题目地址

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

题目描述

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

思路

HashSet for 循环.

关键点

代码

• 语言支持：Java

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

        return false;
    }
}