(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;}