Detect Duplicate Element in a 4×4 Matrix

Program Overview

This Python program reads a 4×4 matrix and checks whether any element appears more than once.
If a duplicate is found, it prints "Yes"; otherwise, it prints "No".

Python Code:

def read_matrix(rows: int, cols: int) -> list[list[int]]:
    print(f"Enter elements for a {rows}×{cols} matrix:")
    matrix = []
    for i in range(rows):
        row = list(map(int, input(f"Row {i+1}: ").strip().split()))
        if len(row) != cols:
            print("Each row must contain exactly the number of columns.")
            exit()
        matrix.append(row)
    return matrix

def has_duplicate(matrix: list[list[int]]) -> str:
    seen = set()
    for row in matrix:
        for val in row:
            if val in seen:
                return "Yes"
            seen.add(val)
    return "No"

# Read and check 4×4 matrix
mat = read_matrix(4, 4)
result = has_duplicate(mat)
print(f"\nIs there a duplicate? {result}")

Sample Output:

Input:  
1 2 3 4  
5 6 7 8  
9 10 11 12  
13 14 15 1  

Output:  
Is there a duplicate? Yes