FindXorSumOfAllPairsBitwiseAnd.cpp

// Source : https://leetcode.com/problems/find-xor-sum-of-all-pairs-bitwise-and/
// Author : Hao Chen
// Date   : 2021-04-20

/***************************************************************************************************** 
 *
 * The XOR sum of a list is the bitwise XOR of all its elements. If the list only contains one 
 * element, then its XOR sum will be equal to this element.
 * 
 * 	For example, the XOR sum of [1,2,3,4] is equal to 1 XOR 2 XOR 3 XOR 4 = 4, and the XOR sum 
 * of [3] is equal to 3.
 * 
 * You are given two 0-indexed arrays arr1 and arr2 that consist only of non-negative integers.
 * 
 * Consider the list containing the result of arr1[i] AND arr2[j] (bitwise AND) for every (i, j) pair 
 * where 0 <= i < arr1.length and 0 <= j < arr2.length.
 * 
 * Return the XOR sum of the aforementioned list.
 * 
 * Example 1:
 * 
 * Input: arr1 = [1,2,3], arr2 = [6,5]
 * Output: 0
 * Explanation: The list = [1 AND 6, 1 AND 5, 2 AND 6, 2 AND 5, 3 AND 6, 3 AND 5] = [0,1,2,0,2,1].
 * The XOR sum = 0 XOR 1 XOR 2 XOR 0 XOR 2 XOR 1 = 0.
 * 
 * Example 2:
 * 
 * Input: arr1 = [12], arr2 = [4]
 * Output: 4
 * Explanation: The list = [12 AND 4] = [4]. The XOR sum = 4.
 * 
 * Constraints:
 * 
 * 	1 <= arr1.length, arr2.length <= 10^5
 * 	0 <= arr1[i], arr2[j] <= 10^9
 ******************************************************************************************************/

class Solution {
public:
    int getXORSum(vector<int>& arr1, vector<int>& arr2) {
        int x = arr1[0];
        for(int i = 1; i < arr1.size(); i++) {
            x ^= arr1[i];
        }
        int y = arr2[0];
        for(int i = 1; i< arr2.size(); i++) {
            y ^= arr2[i];
        }
        return x&y;
    }
};