Difficulty:easy
More:【目录】LeetCode Java实现
Description
https://leetcode.com/problems/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
Intuition
Use HashSet.
Solution
public boolean containsDuplicate(int[] nums) {
if(nums==null || nums.length<=1)
return false;
HashSet<Integer> set = new HashSet<>();
for(int i : nums){
if(set.contains(i)){
return true;
}else{
set.add(i);
}
}
return false;
}
Complexity
Time complexity : O(n)
Space complexity : O(n)
More:【目录】LeetCode Java实现