1835-find-xor-sum-of-all-pairs-bitwise-and.js

/**
 * @param {number[]} arr1
 * @param {number[]} arr2
 * @return {number}
 */
const getXORSum = function(arr1, arr2) {
  let a = 0, b = 0
  for(const e of arr1) a ^= e
  for(const e of arr2) b ^= e
  
  return a & b
};


// another

// On every bit XOR acts as modulo 2 addition and AND acts as modulo 2 multiplication.
// The set {0,1} with modulo 2 addition and multiplication is the field GF(2) and the distributive property holds in every field.

/**
 * @param {number[]} arr1
 * @param {number[]} arr2
 * @return {number}
 */
const getXORSum = function(arr1, arr2) {
  const bits = Array(32).fill(0)
  for (let v of arr2) {
      let pos = 0;
      while (v > 0) {
        if (v & 1) {
          bits[pos]++;
        }
        v = v >> 1;
        pos++;
      }
    }

    let res = 0;

    for (let v of arr1) {
      let pos = 0;
      let tmp = 0;
      while (v > 0) {
        if (v & 1) {
          if (bits[pos] % 2 == 1) {
            tmp |= (1 << pos);
          }
        }
        v = v >> 1;
        pos++;
      }

      res ^= tmp;
    }

    return res;
};

// another

/**
 * @param {number[]} arr1
 * @param {number[]} arr2
 * @return {number}
 */
const getXORSum = function(arr1, arr2) {
  let x1 = arr1[0], x2 = arr2[0]
  for(let i = 1; i < arr1.length; i++) x1 ^= arr1[i]
  for(let i = 1; i < arr2.length; i++) x2 ^= arr2[i]
  return x1 & x2
};