find-the-symmetric-difference.js

/**
 * Algorithms: Find the Symmetric Difference
 *
 * Create a function that takes two or more arrays and returns an array of the symmetric difference (△ or ⊕) of the provided arrays.
 *
 * Given two sets (for example set A = {1, 2, 3} and set B = {2, 3, 4}), the mathematical term "symmetric difference" of two sets is the set of elements which are in either of the two sets, but not in both (A △ B = C = {1, 4}). For every additional symmetric difference you take (say on a set D = {2, 3}), you should get the set with elements which are in either of the two the sets but not both (C △ D = {1, 4} △ {2, 3} = {1, 2, 3, 4}). The resulting array must contain only unique values (no duplicates).
 */

/**
 * Find the Symmetric Difference
 * @author Mike Mai
 * @param {number[]} - accept any number of array
 * @return {number[]}
 *
 * @example
 * sym([1, 2, 3], [5, 2, 1, 4]); //[3, 4, 5]
 */
function sym() {
  const nums = {};
  const ans = [];

  for (let k in arguments) {
    getNums(nums, arguments[k]);
  }

  for (let k in nums) {
    if (nums[k] % 2 !== 0) {
      ans.push(+k);
    }
  }

  return ans;
}

function getNums(nums, arr) {
  let visited = {};
  for (let n of arr) {
    if (visited[n] === undefined) {
      nums[n] = nums[n] || 0;
      nums[n]++;
      visited[n] = true;
    }
  }
}


console.log(sym([1, 2, 3], [5, 2, 1, 4])); //[3, 4, 5]
console.log(sym([1, 2, 3, 3], [5, 2, 1, 4])); // [3, 4, 5]
console.log(sym([1, 2, 3], [5, 2, 1, 4, 5])); // [3, 4, 5]
console.log(sym([1, 2, 5], [2, 3, 5], [3, 4, 5])); // [1, 4, 5]
console.log(sym([1, 1, 2, 5], [2, 2, 3, 5], [3, 4, 5, 5])); // [1, 4, 5]
console.log(sym([3, 3, 3, 2, 5], [2, 1, 5, 7], [3, 4, 6, 6], [1, 2, 3])); // [2, 3, 4, 6, 7]
console.log(sym([3, 3, 3, 2, 5], [2, 1, 5, 7], [3, 4, 6, 6], [1, 2, 3], [5, 3, 9, 8], [1])); // [1, 2, 4, 5, 6, 7, 8, 9]