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.
题目：一言蔽之，如果一个数组中有元素出现多于一次，就返回true，要是每个元素都是唯一的，返回false
思路：没思路。。。直接上代码，
public boolean containsDuplicate(int[] nums) {
Set<Integer> set = new HashSet<Integer>();
for(int i = 0 ;i<nums.length;i++){
if(set.contains(nums[i])){
return true;
}
set.add(nums[i]);
}
return false;
}