Details: http://codingdragon.tumblr.com/post/65055120905/rotate-matrix-by-90-degrees

RotateMatrix.cpp

template<int N>
void rotate90Clockwise(int (&matrix)[N][N]){
    //Transpose the matrix
    int temp;
    for(int i=0;i<N;i++){
        for(int j=0;j<i;j++){
            temp=matrix[i][j];
            matrix[i][j]=matrix[j][i];
            matrix[j][i]=temp;
        }
    }
    //For clockwise rotation reverse rows, for anti-clockwise reverse columns
    for(int i=0;i<N;i++){
        for(int j=0;j<N/2;j++){
            temp = matrix[i][j];
            matrix[i][j] = matrix[i][N-j-1];
            matrix[i][N-j-1] = temp;
        }
    }
}