Given an array of integers, every element appears twice except for one. Find that single one. Note: Your algorithm should have a linear runtime complexity. Could you implement it without using ext

Implement int sqrt(int x). Compute and return the square root of x. 这个题目我做了很长一段时间才通过，原因有很多，但是最头痛的是超时和越界； 最后看了别人的代码才知道用二分，，，， 要用unsigned long long，不然会越界； class Solution { public: int