两个数组的交集 II

const intersect = function(nums1, nums2) {
    const hashMap = new Map()
    const res = []

    for (let i = 0; i < nums1.length; i++) {
        const  v = hashMap.get(nums1[i])
        
        if (!v)
            hashMap.set(nums1[i], 1)
        else
            hashMap.set(nums1[i], v + 1)
    }

    for (let i = 0; i < nums2.length; i++) {
        const  v = hashMap.get(nums2[i])

        if (v > 0){
            res.push(nums2[i])
            hashMap.set(nums2[i], v - 1)
        }
        if (v === 0)
            hashMap.delete(nums2[i])
    }

    return res
};