_268.java

package com.fishercoder.solutions;

/**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?*/

public class _268 {

    /**we could take advantage of the array indices
    then a number xor with itself is zero, so after we xor the entire array with all of its indices, the missing number will show up.*/
    public int missingNumber(int[] nums) {
        int xor = 0;
        int i = 0;
        for (; i < nums.length; i++) {
            xor = xor ^ i ^ nums[i];
        }
        return xor ^ i;
    }

}