MissingNumber.java

/*
Question No. 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.

 

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.

Example 3:

Input: nums = [9,6,4,2,3,5,7,0,1]
Output: 8
Explanation: n = 9 since there are 9 numbers, so all numbers are in the range [0,9]. 8 is the missing number in the range since it does not appear in nums.

 

Constraints:

    n == nums.length
    1 <= n <= 104
    0 <= nums[i] <= n
    All the numbers of nums are unique.


*/
class Solution {
    public int missingNumber(int[] nums) {
        /*
        Brute Force
        int n=nums.length;
        int sum=0;
        int sum1=0;
        int max=0;

        for(int i=0;i<n;i++){
            sum=sum+nums[i];//sum=(n*(n+1))/2
        }
        for(int i=0;i<=n;i++){
            sum1=sum1+i;
        }

        return sum1-sum;
        */

        //Bit Manipulation
        int a=0;
        int b=0;
        int n=nums.length;

        for(int i=0;i<=n;i++) a=a^i;
        for(int i=0;i<n;i++) b=b^nums[i];

        return a^b;
                
    }
}