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1. Check if Array is Sorted (Ascending)2. Check if Array is Sorted (Descending)3. Find Second Largest4. Find Second Smallest5. Range (Max - Min)6. Sum Except Max & Min7. Count Pairs with Sum K8. Count Elements Greater Than Average9. Frequency of Distinct Elements10. Unique Elements Only11. Find Kth Largest Element12. Rotate Array by K Positions13. Find Missing Number in Sequence14. Find Duplicate Element

Count Pairs with Sum K

Count pairs of elements whose sum equals k.

AdvancedPhase 4 - Level 5: Logical & AppliedExample 7 of 14
count-pairs-with-sum-k.py
1# Take array
2n = int(input("Enter array size: "))
3arr = []
4for i in range(n):
5    arr.append(int(input(f"Element {i+1}: ")))
6

7k = int(input("Enter target sum: "))
8

9# Count pairs
10count = 0
11for i in range(len(arr)):
12    for j in range(i + 1, len(arr)):
13        if arr[i] + arr[j] == k:
14            count += 1
15

16print(f"Number of pairs with sum {k}: {count}")

Output

Enter array size: 5
Element 1: 2
Element 2: 4
Element 3: 3
Element 4: 5
Element 5: 1
Enter target sum: 6
Number of pairs with sum 6: 2

What's going on

Check all pairs using nested loops.

Key Concepts:

Outer loop: first element
Inner loop: second element (i+1 to avoid duplicates)
Count if sum equals k

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