missing number

Missiong 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?

代码一(14ms):

public class Solution {
    public int missingNumber(int[] nums) {
        Arrays.sort(nums);
        int index = 0;
        for (int i = 0; i < nums.length; i++) {
            index = i;
            if (nums[i] != i) {
                return i;
            }
        }
        return index + 1;
    }
}