(java)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:将1.....n加起来，然后减去nums[0].....nums[n-1]

代码如下(已通过leetcode)

public int missingNumber(int[] nums) {  

int len =nums.length;  

int sum = (int)((len*(len+1))/2); 

for(int i: nums)  

sum-=i;  

return sum;}