268 Missing Number

Given an array nums containing n distinct numbers in the range [0, n], return the only number in the range that is missing from the array.

Follow up: Could you implement a solution using only O(1) extra space complexity and O(n) runtime complexity?

Example 1:

Input: nums = [3,0,1]
Output: 2
Explanation: n = 3 since there are 3 numbers, so all numbers are in the range [0,3]. 2 is the missing number in the range since it does not appear in nums.
Example 2:

Input: nums = [0,1]
Output: 2
Explanation: n = 2 since there are 2 numbers, so all numbers are in the range [0,2]. 2 is the missing number in the range since it does not appear in nums.

JAVA CODE
class Solution {
    public int missingNumber(int[] nums) {
      
     int n = nums.length;//10
     int expectedTotal = (n*(n+1))/2; //55
    
     int total = 0;
     for(int num:nums){
         total += num;
     }
        
     return expectedTotal-total;
    
    
    }
}