intersection-of-two-arrays-ii.js

// Given two arrays, write a function to compute their intersection.
//
//
// Example:
// Given nums1 = [1, 2, 2, 1], nums2 = [2, 2], return [2, 2].
//
//
// Note:
//
// Each element in the result should appear as many times as it shows in both arrays.
// The result can be in any order.
//
//
//
// Follow up:
//
// What if the given array is already sorted? How would you optimize your algorithm?
// What if nums1's size is small compared to nums2's size? Which algorithm is better?
// What if elements of nums2 are stored on disk, and the memory is limited such that you cannot load all elements into the memory at once?


/**
 * @param {number[]} nums1
 * @param {number[]} nums2
 * @return {number[]}
 */
var intersect = function(nums1, nums2) {
    const hashTab = {};
    const result = [];
    for (var i = 0, l = nums1.length; i < l; i++) {
        if (!hashTab[nums1[i]]) {
            hashTab[nums1[i]] = 1;
        } else {
            hashTab[nums1[i]]++;
        }
    }
    for (i = 0, l = nums2.length; i < l; i++) {
        if (hashTab[nums2[i]]) {
            hashTab[nums2[i]]--;
            result.push(nums2[i]);
        }
    }
    return result;
};