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How I can do this in python ?

+6 votes
asked Feb 16 by Shahriyor Yuldashev (690 points)

n is equal to the number of columns of a matrix and the number of rows of a matrix. n is given. And you should make nxn - matrix. If n is equal to 5, the values of the matrix should be as shown below.

matrix = [[1, 2, 3, 4, 5], 

               [16, 17, 18, 19, 6],

               [15, 24, 25, 20, 7],

               [14 ,23, 22, 21, 8], 

               [13, 12, 11, 10, 9]]

Or if n is equal to 3, the values of the matrix should be as shown below.

matrix = [[1, 2, 3], 

                 [8, 9, 4],

                 [7, 6, 5]]

That is, the values of the matrix should be as a circle. How I can do this in python?

1 Answer

+1 vote
answered Feb 16 by Peter Minarik (55,660 points)
edited Feb 17 by Peter Minarik

So basically you'll need to fill up a matrix in a spiral pattern.

Here's a pseudo-code for it so you can write the actual Python code (it's an assignment, you should work on it and not just simply get a ready solution). Of course, there are many solutions, this is just one proposal.

The idea is to use a state machine to follow the spiral pattern: move right, then down, then left, then up and then it starts over until the whole matrix is filled.

var n = InputFromUser();
var array[n, n];
var horizontal_min = 0;
var horizontal_max = n - 1;
var vertical_min = 0;
var vertical_max = n - 1;
var totalNumbers = n * n;

var x = horizontal_min;
var y = vertical_min;

enum States { horizontal_plus, vertical_plus, horizontal_minus, vertical_minus }

var state = States.horizontal_plus;

for (i = 1; i <= totalNumbers; i++)
    array[x, y] = i;
    switch (state)
        case horizontal_plus:
            x++;
            if (x == horizontal_max)
                state = vertical_plus;
                vertical_min++;
        case vertical_plus:
            y++;
            if (y == vertical_max)
                state = horizontal_minus;
                horizontal_max--;
        case horizontal_minus:
            x--;
            if (x == horizontal_min)
                state = vertical_minus;
                vertical_max--;
        case vertical_minus:
            y--;
            if (y == vertical_min)
                state = horizontal_plus;
                horizontal_min++;

Good luck!

commented Feb 16 by Shahriyor Yuldashev (690 points)
Woo Thank you!
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