44.leetcode题目：268. Missing Number（位操作没想到）

题目：

Given an array containing n distinct numbers taken from 0, 1, 2, ..., n, find the one that is missing from the array.

For example,
Given nums = [0, 1, 3] return 2.

Note:
Your algorithm should run in linear runtime complexity. Could you implement it using only constant extra space complexity?

分析：

我觉得好类似于脑筋急转弯啊，简单，不写了。但是好像可以用位操作，对位操作不熟练。