Check Duplicate
出处
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.
Solution
用一个哈希表检测即可
Complexity
时间复杂度 O(n),空间复杂度 O(n)
Code
public class Solution {
public boolean containsDuplicate(int[] nums) {
if(nums==null || nums.length==0)
return false;
HashSet<Integer> set = new HashSet<Integer>();
for(int i: nums){
if(!set.add(i)){
return true;
}
}
return false;
}
}