###217. Contains Duplicate

题目:
<https://leetcode.com/problems/contains-duplicate/>


难度:

Easy 


我直接sort，然后比较相邻的元素，这样O(n)，也是笨办法，居然unlocked a solution，所以来读读解答.

三个办法：

- linear search O(n^2)
- sort O(n)
- hashtable


我用的sort

```
class Solution(object):
    def containsDuplicate(self, nums):
        """
        :type nums: List[int]
        :rtype: bool
        """
        nums.sort()
        for i in range(len(nums)-1):
            if nums[i] == nums[i+1]:
                return True
        return False
```




看给的Java解法


```
public boolean containsDuplicate(int[] nums) {
    Set<Integer> set = new HashSet<>(nums.length);
    for (int x: nums) {
        if (set.contains(x)) return true;
        set.add(x);
    }
    return false;
}
```

还有一个取巧的Python解法，我也看到了

```
class Solution(object):
    def containsDuplicate(self, nums):
        if len(nums) > len(set(nums)):
            return True
        return False
```