268. Missing Number

// Runtime: 6 ms, faster than 12.23% of Java online submissions for Missing Number.
// Memory Usage: 39.3 MB, less than 81.66% of Java online submissions for Missing Number.

// class Solution {
//     public int missingNumber(int[] nums) {
//         HashSet<Integer> set=new HashSet<>();
        
//         for(int i:nums){
//             set.add(i);
//         }
//         for(int i=0;i<nums.length;i++)
//         {
//             if(!set.contains(i))
//                 return i;
//         }
        
        
//         return nums.length;
//         }
    
// }


class Solution {
    public int missingNumber(int[] nums) {
        int a=0;
        for(int i=0;i<=nums.length;i++)
        {
            a=a^i;
        }
        
         int b=0;
        for(int i=0;i<nums.length;i++)
        {
            b=b^nums[i];
        }
        int res=a^b;
        return res;
    }
}
//Memory Usage: 40.1 MB, less than 100.00% of Java online submissions for Missing Number.