268. Missing Number

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?

思路：

因为只有一个数字不见了，所以和标准的数组异或得到的结果就是不见的数字

public int missingNumber(int[] nums) {
int res = 0;
for (int i = 0; i <= nums.length; i++) {
res ^= i == nums.length ? i : i ^ nums[i];
}
return res;
}