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Python3 Program to Rotate the matrix right by K times

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  • Last Updated : 08 Jun, 2022

Given a matrix of size N*M, and a number K. We have to rotate the matrix K times to the right side. 
Examples: 
 

Input :  N = 3, M = 3, K = 2
         12 23 34
         45 56 67
         78 89 91 

Output : 23 34 12
         56 67 45
         89 91 78 


Input :  N = 2, M = 2, K = 2
         1 2
         3 4
         
Output : 1 2
         3 4

 

A simple yet effective approach is to consider each row of the matrix as an array and perform an array rotation. This can be done by copying the elements from K to end of array to starting of array using temporary array. And then the remaining elements from start to K-1 to end of the array.
Lets take an example: 
 

 

Python3




# Python program to rotate
# a matrix right by k times
 
# size of matrix
M = 3
N = 3
matrix = [[12, 23, 34],
          [45, 56, 67],
          [78, 89, 91]]
 
# function to rotate
# matrix by k times
def rotateMatrix(k) :
 
    global M, N, matrix
     
    # temporary array
    # of size M
    temp = [0] * M
     
    # within the size
    # of matrix
    k = k % M
     
    for i in range(0, N) :
     
        # copy first M-k elements
        # to temporary array
        for t in range(0, M - k) :
            temp[t] = matrix[i][t]
     
        # copy the elements from
        # k to end to starting
        for j in range(M - k, M) :
            matrix[i][j - M + k] = matrix[i][j]
     
        # copy elements from
        # temporary array to end
        for j in range(k, M) :
            matrix[i][j] = temp[j - k]
     
# function to display
# the matrix
def displayMatrix() :
 
    global M, N, matrix
    for i in range(0, N) :
     
        for j in range(0, M) :
            print ("{} " .
                   format(matrix[i][j]), end = "")
        print ()
 
# Driver code
k = 2
 
# rotate matrix by k
rotateMatrix(k)
 
# display rotated matrix
displayMatrix()
 
# This code is contributed by
# Manish Shaw(manishshaw1)

Output: 

23 34 12 
56 67 45 
89 91 78

 

Time Complexity: O(N*M) 
Auxiliary Space: O(M)

Please refer complete article on Rotate the matrix right by K times for more details!


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