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Python Program to Interchange elements of first and last rows in matrix

  • Last Updated : 24 May, 2022

Given a 4 x 4 matrix, we have to interchange the elements of first and last row and show the resulting matrix.
Examples : 
 

Input : 3 4 5 0
        2 6 1 2
        2 7 1 2
        2 1 1 2
Output : 2 1 1 2
         2 6 1 2
         2 7 1 2
         3 4 5 0

Input : 9 7 5 1
        2 3 4 1
        5 6 6 5
        1 2 3 1
Output : 1 2 3 1
         2 3 4 1
         5 6 6 5
         9 7 5 1

 

The approach is very simple, we can simply swap the elements of first and last row of the matrix inorder to get the desired matrix as output.
Below is the implementation of the approach : 
 

Python3




# Python code to swap the element
# of first and last row and display
# the result
 
def interchangeFirstLast(mat, n, m):
    rows = n
     
    # swapping of element between
    # first and last rows
    for i in range(n):
        t = mat[0][i]
        mat[0][i] = mat[rows-1][i]
        mat[rows-1][i] = t
 
# Driver Program
mat = [[8, 9, 7, 6],
          [4, 7, 6, 5],
       [3, 2, 1, 8],
       [9, 9, 7, 7]]
 
n = 4
m = 4
interchangeFirstLast(mat, n, m)
 
# printing the interchanged matrix
for i in range(n):
    for j in range(m):
        print(mat[i][j], end = " ")
    print("
")
 
# This code is contributed by Shrikant13.

Output : 
 

9 9 7 7 
4 7 6 5 
3 2 1 8 
8 9 7 6 

Time Complexity: O(N)

Auxiliary Space: O(1)

Please refer complete article on Interchange elements of first and last rows in matrix for more details!

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