Python : Common Elements Between Two Arrays

Video 100: In this exercise, we find the common elements between two arrays.

You are given two integer arrays nums1 and nums2 of sizes n and m, respectively.

Consider calculating the following values:
1. The element in nums1 occurs at least once in nums2.
2. The element in nums2 occurs at least once in nums1.
Return an integer array answer of size 2 containing the two values in the above order.

We addressed this question in three different ways.

*** Approach 1: Convert the input array to a dictionary and check ***
In this approach, we convert the input array to a dictionary format, where the key is the element, and the value is the number of times the element occurs in the array. Then, we loop through the input array and check if the element in nums1 array exists in dictionary2 and the same way for nums2 array. Return the count as an array in the proper order.

*** Approach 2: Directly compare two arrays ***
In this approach, we loop through each element of one array and check if that element exists in the other array. Return the count as an array in the proper order.

*** Approach 3: Convert the input array to a set and check ***
In this approach, we convert the input array to a set variable. Then, we loop through the input array and check if the element in nums1 array exists in the set2 and the same way for nums2 array. Return the count as an array in the proper order.

Using a dictionary for membership testing (in operation) can be more efficient than using a list when you have a large dataset. The reason is that dictionary lookups have an average time complexity of O(1), while list lookups have a time complexity of O(n) in the worst case.

Using a Dictionary:
Pros: Faster lookup time, especially for large datasets.
Cons: Requires extra memory to store the dictionary.

Directly Checking in a List:
Pros: No additional memory overhead.
Cons: Slower lookup time for large datasets.

For an in-depth understanding of these Python code, please refer to the comprehensive explanatory video.

Follow me on,

#recursive #countingalgorithm #list #looping #listmanipulation #uniquesubstring #longestsubstring #slicing #lineartimecomplexity #python #pythonquestions #pythontest #pythonprogramming #pythontutorial #python3 #pythonforbeginners #interviewquestions #interview #dataengineers #deinterview #pythoninterview #interviewquestions #leetcode #placementpreparation #meta #google #facebook #apple #netflix #amazon #google #faang #maanga #dataengineers #alphanumeric #nonalphanumeric #growwithdata #set #split #remove #pythonfunctions