C++ Program to Rotate Matrix Elements
Last Updated :
22 Aug, 2023
Given a matrix, clockwise rotate elements in it.
Examples:
Input:
1 2 3
4 5 6
7 8 9
Output:
4 1 2
7 5 3
8 9 6
For 4*4 matrix:
Input:
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
The idea is to use loops similar to the program for printing a matrix in spiral form. One by one rotate all rings of elements, starting from the outermost. To rotate a ring, we need to do following.
1) Move elements of top row.
2) Move elements of last column.
3) Move elements of bottom row.
4) Move elements of first column.
Repeat above steps for inner ring while there is an inner ring.
Below is the implementation of above idea.
C++
#include <iostream>
#define R 4
#define C 4
using namespace std;
void rotatematrix( int m, int n,
int mat[R][C])
{
int row = 0, col = 0;
int prev, curr;
while (row < m && col < n)
{
if (row + 1 == m ||
col + 1 == n)
break ;
prev = mat[row + 1][col];
for ( int i = col; i < n; i++)
{
curr = mat[row][i];
mat[row][i] = prev;
prev = curr;
}
row++;
for ( int i = row; i < m; i++)
{
curr = mat[i][n-1];
mat[i][n-1] = prev;
prev = curr;
}
n--;
if (row < m)
{
for ( int i = n-1; i >= col; i--)
{
curr = mat[m-1][i];
mat[m-1][i] = prev;
prev = curr;
}
}
m--;
if (col < n)
{
for ( int i = m-1; i >= row; i--)
{
curr = mat[i][col];
mat[i][col] = prev;
prev = curr;
}
}
col++;
}
for ( int i=0; i<R; i++)
{
for ( int j=0; j<C; j++)
cout << mat[i][j] << " " ;
cout << endl;
}
}
int main()
{
int a[R][C] = {{1, 2, 3, 4},
{5, 6, 7, 8},
{9, 10, 11, 12},
{13, 14, 15, 16}};
rotatematrix(R, C, a);
return 0;
}
|
Output:
5 1 2 3
9 10 6 4
13 11 7 8
14 15 16 12
Time Complexity: O(max(m,n) * max(m,n))
Auxiliary Space: O(m*n)
Please refer complete article on Rotate Matrix Elements for more details!
Share your thoughts in the comments
Please Login to comment...