c++ table spiral algorithm output

Question

#include <iostream>
#include <iomanip>
using namespace std;
int main()
{
    int arraysize;
    cout<<"Size: ";
    cin>>arraysize;
    int a[arraysize][arraysize];
    int couter = 1, stepTop = 0, stepLeft = 1, stepBottom = 0, stepRight = 1;
    for(int iMain = 0; iMain < ((arraysize / 2) + 1); iMain++)
    {
        for(int i = stepTop; i < stepTop + 1; i++)
        {
            for(int j = stepTop; j < (arraysize - stepTop); j++)
            {

                a[i][j] = couter;
                couter++;
            }

        }
        stepTop++;

        if(iMain < (arraysize / 2))
        {
            for(int i = stepRight; i <= (arraysize - stepRight - 1); i++)
            {
                for(int j = (arraysize - stepRight); j < (arraysize - stepRight + 1); j++)
                {
                    a[i][j] = couter;
                    couter++;
                }
            }
            stepRight++;

            for(int i = (arraysize - 1 - stepBottom); i >= (arraysize - stepBottom - 1); i--)
            {
                for(int j = (arraysize - 1 - stepBottom); j >= stepBottom; j--)
                {
                    a[i][j] = couter;
                    couter++;
                }
            }
            stepBottom++;

            for(int i = (arraysize - stepLeft - 1); i >= stepLeft; i--)
                {
                for(int j = stepLeft; j < stepLeft; j++)
                {
                    a[i][j] = couter;
                    couter++;
                }
            }
            stepLeft++;
        }
    }


for(int i = 0; i < arraysize; i++)
    {
        for(int j = 0; j < arraysize; j++)
        {
            cout<<setw(arraysize)<<a[i][j];
            cout<<" ";
        }
        cout<<endl;
    }

    return 0;
}

The problem is when the program output the numbers they are like:

Size: 6
     1      2      3      4      5      6
2686500     17     18     19     20      7
     1 2686336     27     28     21      8
4651536 2686512     30     29     22      9
     0     26     25     24     23     10
    16     15     14     13     12     11

Process returned 0 (0x0) execution time : 0.577 s Press any key to continue.

Image http://imgur.com/kjABBWr

Its doing the spiral but some of the numbers are big like 2686500 — user3290421, Apr 27 '15 at 14:07
Some of the numbers are too big for this i make 6 by 6 table and some of the numbers are random not from 1 to 30 — user3290421, Apr 27 '15 at 14:11
6x6 would make 36 elements and it appears as if 5 of them you never assign a value. Thus what you get in the output is just rubbish. What is the value of your counter when you are finished assigning values? I would bet that it is 31 and not 36, i.e. you are missing some elements. — 463035818_is_not_an_ai, Apr 27 '15 at 14:15
http://stackoverflow.com/questions/398299/looping-in-a-spiral — 463035818_is_not_an_ai, Apr 27 '15 at 14:15
I am input size 6 and its starting and finish with some big numbers — user3290421, Apr 27 '15 at 14:16
why dont you put the output in a format such that you can see the matrix? I guess then it will be easier to find out what is going on — 463035818_is_not_an_ai, Apr 27 '15 at 14:21
I think the best way to find where is the bug is to run it in debug mode and go step by step to see what's append, specially when build the 2D-array — Garf365, Apr 27 '15 at 14:24

Ayushi Jha · Answer 1 · 2015-04-27T15:01:51.377

0

Just a small change : this->for(int j = stepLeft; j <= stepLeft; j++) to this: for(int j = stepLeft-1; j < stepLeft; j++)

Ideone link: https://ideone.com/kR8nOZ

edited Apr 27 '15 at 15:01

answered Apr 27 '15 at 14:32

Ayushi Jha

4,003
3
26
43

Still false as you increase by 2 instead of 1 when you go up. – Jarod42 Apr 27 '15 at 14:39

c++ table spiral algorithm output

1 Answers1