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1. Compare Arrays (Same Order)2. Compare Arrays (Ignore Order)3. Merge Two Arrays4. Find Common Elements5. Elements in A Not in B6. Count Common Elements7. Element-wise Sum8. Element-wise Product9. Frequency Array10. Elements Appearing More Than Once

Count Common Elements

Count number of common elements.

IntermediatePhase 4 - Level 4: Aggregation & ComparisonExample 6 of 10
count-common-elements.py
1# Take arrays
2n1 = int(input("Enter size of first array: "))
3arr1 = []
4for i in range(n1):
5    arr1.append(int(input(f"Array1 element {i+1}: ")))
6

7n2 = int(input("Enter size of second array: "))
8arr2 = []
9for i in range(n2):
10    arr2.append(int(input(f"Array2 element {i+1}: ")))
11

12# Count common
13common_set = set(arr1) & set(arr2)
14count = len(common_set)
15

16print(f"Number of common elements: {count}")

Output

Enter size of first array: 4
Array1 element 1: 1
Array1 element 2: 2
Array1 element 3: 3
Array1 element 4: 2
Enter size of second array: 3
Array2 element 1: 2
Array2 element 2: 3
Array2 element 3: 4
Number of common elements: 2

What's going on

Use set intersection to find common elements.

Key Concepts:

Convert to sets
Use & operator for intersection
Count unique common elements

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