Rotate a matrix 90 degrees cloclwise

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Hello , i'm struggling to find an algorithm that will rotate a matrix (multidimensional array) 90 degrees clockwise. I cant use any functions (transcope etc), Basically i need to write the code on my own. Any tips?

thanks!

Posted 16-Dec-14 21:05pm

Daniel Mashukov

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Comments

Legor 17-Dec-14 3:25am

What datatype are you using as a matrice?

Daniel Mashukov 17-Dec-14 3:37am

Int

Legor 18-Dec-14 3:20am

No i mean how is your matrice defined? E.g. is it a vector of vectors or a 2D array like a[100][100] ?

Daniel Mashukov 19-Dec-14 2:31am

2D array

2 solutions

Solution 2

C#

for (int i = 0; i < rows; i++)
    {
        for (int j = i + 1; j < col; j++)
        {
            temp = arr[i][j];
            arr[i][j] = arr[j][i];
            arr[j][i] = temp;
        }
    }

    for (int i = 0; i < rows; i++)
    {
        for (int j = 0; j < col / 2; j++)
        {
            temp = arr[i][j];
            arr[i][j] = arr[i][col - 1 - j];
            arr[i][col - 1 - j] = temp;
        }

Posted 18-Dec-14 20:33pm

Daniel Mashukov

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Member 10641779 · Accepted Answer · 2014-12-16T22:22:00

Try something like this
suppose matrice a of size (n x m)

C++

for(int i=0; i<n;i++)
{
    for(int j=m-1; j>=0;j--)
    {
        printf("%d ", a[j][i]);  //in C
        cout<<a[j][i];          //in C++
    }
    printf("\n"); or  //cout<<endl;
}

if you want to save it to other matrix:
Take another matrix, say b of size (n x m)

C++

int x = 0;
for(int i=0; i<n;i++)
{
    for(int j=m-1; j>=0;j--)
    {
        printf("%d ", a[j][i]);  //in C
        cout<<a[j][i];          //in C++
        b[i][x++] = a[j][i]; 
    }
    x = 0;
    printf("\n"); or  //cout<<endl;
}

if you matrix is
1 2
3 4
it will return
3 1
4 2