Intersection of Two Arrays II

Author: anantkaushik

350-intersection-of-two-arrays-ii.py

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+"""
+Problem Link: https://leetcode.com/problems/intersection-of-two-arrays-ii/
+
+Given two arrays, write a function to compute their intersection.
+
+Example 1:
+Input: nums1 = [1,2,2,1], nums2 = [2,2]
+Output: [2,2]
+
+Example 2:
+Input: nums1 = [4,9,5], nums2 = [9,4,9,8,4]
+Output: [4,9]
+
+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?
+"""
+class Solution(object):
+    def intersect(self, nums1, nums2):
+        """
+        :type nums1: List[int]
+        :type nums2: List[int]
+        :rtype: List[int]
+        """
+        dic = {}
+        for a in nums1:
+            dic[a] = dic.get(a, 0) + 1
+        res = []
+        for a in nums2:
+            if a in dic and dic[a] > 0:
+                res.append(a)
+                dic[a] -= 1
+        return res