Programming Assignment 2: Rotate the matrix
Due on 2020-11-05, 23:59 IST
Given a square matrix with n rows and n columns, you have to write a program to rotate this matrix such that each element is shifted by one place in a clockwise manner.
For example, given the following matrix
1 2 3
4 5 6
7 8 9
The output should be
4 1 2
7 5 3
8 9 6
Input Format:
The first line of the input contains a number n representing the number of rows and columns.
After this, there are n rows with each row containing n elements separated by a space
Output Format:
Print the elements of the modified matrix with each row in a new line and all the elements in each row is separated by a space.
Example 1:
Input:
3
1 2 3
4 5 6
7 8 9
Output:
4 1 2
7 5 3
8 9 6
Example 2:
Input:
4
1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16
Output:
5 1 2 3
9 10 6 4
13 11 7 8
14 15 16 12
Explanation:
In the first example, there is an odd number of rows and columns hence excluding the middle element i.e. 5 all the elements were shifted by one position in a clockwise manner.
In the second example, there are even number of rows and columns hence all the elements were shifted by one position in a clockwise manner.
# Python program to rotate a matrix
# Function to rotate a matrix
def rotateMatrix(mat):
if not len(mat):
return
"""
top : starting row index
bottom : ending row index
left : starting column index
right : ending column index
"""
top = 0
bottom = len(mat)-1
left = 0
right = len(mat[0])-1
while left < right and top < bottom:
# Store the first element of next row,
# this element will replace first element of
# current row
prev = mat[top+1][left]
# Move elements of top row one step right
for i in range(left, right+1):
curr = mat[top][i]
mat[top][i] = prev
prev = curr
top += 1
# Move elements of rightmost column one step downwards
for i in range(top, bottom+1):
curr = mat[i][right]
mat[i][right] = prev
prev = curr
right -= 1
# Move elements of bottom row one step left
for i in range(right, left-1, -1):
curr = mat[bottom][i]
mat[bottom][i] = prev
prev = curr
bottom -= 1
# Move elements of leftmost column one step upwards
for i in range(bottom, top-1, -1):
curr = mat[i][left]
mat[i][left] = prev
prev = curr
left += 1
return mat
# Utility Function
def printMatrix(mat,n):
for i in range(n):
for j in range(n):
if(j==n-1):
print(mat[i][j],end="")
else:
print(mat[i][j],end=" ")
if(i!=n-1):
print()
n = int(input())
matrix = []
for i in range(1,n+1):
l = list(map(int, input ().split ()))
matrix.append(l)
matrix = rotateMatrix(matrix)
# Print modified matrix
printMatrix(matrix,n)
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