Convert 1D to 2D ORDERING spiral starting from the center - c++

Question

sorry for bothering but I'm stuck in this, the idea is:
Insert in console numbers from 1 to 9 (it doesn't matter the order or if it repeat), and create a 2 dimensional array BUT it has to be order in SPIRAL INVERSE (starting from the center)
EXAMPLE 1:
INPUT (enter numbers without spaces):
123456789
OUTPUT:
789
612
543
EXAMPLE 2:
INPUT (enter numbers without spaces):
12345678976
OUTPUT:
7897
6126
543
I MADE THIS:
for getting the numbers and trying to put in vector of 2 dimensions but after that point I don't know how I should make the spiral...
attached my code:
#include <iostream>
using namespace std;
int main()
{
int a[] = { 1,2,3,4,5,6,7,8,9 };
int b[3][3];
int k = 0;
int i, j;
int arrSize = sizeof(a) / sizeof(a[0]);
cout << arrSize;
cout << endl;
for (i = 0; i < 3; i++)
for (j = 0; j < 3; j++)
b[i][j] = a[k++];
for (i = 0; i < 3; i++)
{
for (j = 0; j < 3; j++)
cout << b[i][j];
cout << endl;
}
}
With this code I be able to put into a 2D array.
Thank you in advance, for your time and patience with me!

Answer 1

The following program lists the (x, y) sequence for the spiral. The first list using the starting points located at (0, 0). The second moves the starting of spiral to the position of (minimum.x, minimum.y). The minimum keeps the coordinate of the left-bottom element.
You may observe the rule of spiral in the program. A position (x,y) first starts at (n, n-1) where n is the nth loop of the spiral. First, move the position downward, --y, untile y reach -n; then move x left until x = -n; then move y upward until y=n; finally, move x right until x = n. In the following program max(n) set = 4, there are 4 spiral loops. You may adjust this parameter n to fit you purpose.
The total number of each spiral loop = 8*n, except the inner most loop (0,0), the number = 1. Therefore, the number of element of spiral = 1 + 8*1 + 8*2 + 8*3 +.... You have first to determine the loops of spiral by the length of input string L, The loops number is eqaul to `n = ( (L-1) / 8 + 1 );` or `n = ( (L-1) / 8 );` if no remaider left.
#include <iostream>
#include <vector>
struct int2 {
int x, y;
int2():x(0), y(0) {}
int2(const int a, const int b):x(a), y(b) {}
int2& operator=(const int2&) = default;
void print() const {std::cout << "( " << x <<", " << y << ") "; }
int2& operator+=(const int2&a) { this->x += a.x ; this->y += a.y; return *this;}
int2& operator-() {x = -x; y = -y; return *this;}
};
int main()
{
std::vector<int2> spiral;
int2 pos, minimum;
int n;
pos = int2(0,0);
minimum = pos;
spiral.push_back(pos);
for (n=1; n<5; n++)
{
pos = int2( n, n-1); // starting point for ith loop
spiral.push_back(pos);
while (pos.y > -n) {--pos.y; spiral.push_back(pos); if (pos.y < minimum.y) minimum.y = pos.y;}
while (pos.x > -n) {--pos.x; spiral.push_back(pos); if (pos.x < minimum.x) minimum.x = pos.x; }
while (pos.y < n) {++pos.y; spiral.push_back(pos); }
while (pos.x < n) {++pos.x; spiral.push_back(pos); }
}
-minimum;
std::cout << "center at (0, 0)\n";
for (int i=0; i<spiral.size(); i++) spiral[i].print();
std::cout<<std::endl;
for (int i=0; i<spiral.size(); i++) spiral[i] += minimum;
std::cout << "center at "; minimum.print(); std::cout<<std::endl;
for (int i=0; i<spiral.size(); i++) spiral[i].print();
std::cout<<std::endl;
return 0;
}
This above (x, y) positions provide you the 2-d sequence array[x][y] to write you char forming a spiral structure.
center at (0, 0)
( 0, 0) ( 1, 0) ( 1, -1) ( 0, -1) ( -1, -1) ( -1, 0) ( -1, 1) ( 0, 1) ( 1, 1) ( 2, 1) ( 2, 0) ( 2, -1) ( 2, -2) ( 1, -2) ( 0, -2) ( -1, -2) ( -2, -2) ( -2, -1) ( -2, 0) ( -2, 1) ( -2, 2) ( -1, 2) ( 0, 2) ( 1, 2) ( 2, 2) ( 3, 2) ( 3, 1) ( 3, 0) ( 3, -1) ( 3, -2) ( 3, -3) ( 2, -3) ( 1, -3) ( 0, -3) ( -1, -3) ( -2, -3) ( -3, -3) ( -3, -2) ( -3, -1) ( -3, 0) ( -3, 1) ( -3, 2) ( -3, 3) ( -2, 3) ( -1, 3) ( 0, 3) ( 1, 3) ( 2, 3) ( 3, 3) ( 4, 3) ( 4, 2) ( 4, 1) ( 4, 0) ( 4, -1) ( 4, -2) ( 4, -3) ( 4, -4) ( 3, -4) ( 2, -4) ( 1, -4) ( 0, -4) ( -1, -4) ( -2, -4) ( -3, -4) ( -4, -4) ( -4, -3) ( -4, -2) ( -4, -1) ( -4, 0) ( -4, 1) ( -4, 2) ( -4, 3) ( -4, 4) ( -3, 4) ( -2, 4) ( -1, 4) ( 0, 4) ( 1, 4) ( 2, 4) ( 3, 4) ( 4, 4)
center at ( 4, 4)
( 4, 4) ( 5, 4) ( 5, 3) ( 4, 3) ( 3, 3) ( 3, 4) ( 3, 5) ( 4, 5) ( 5, 5) ( 6, 5) ( 6, 4) ( 6, 3) ( 6, 2) ( 5, 2) ( 4, 2) ( 3, 2) ( 2, 2) ( 2, 3) ( 2, 4) ( 2, 5) ( 2, 6) ( 3, 6) ( 4, 6) ( 5, 6) ( 6, 6) ( 7, 6) ( 7, 5) ( 7, 4) ( 7, 3) ( 7, 2) ( 7, 1) ( 6, 1) ( 5, 1) ( 4, 1) ( 3, 1) ( 2, 1) ( 1, 1) ( 1, 2) ( 1, 3) ( 1, 4) ( 1, 5) ( 1, 6) ( 1, 7) ( 2, 7) ( 3, 7) ( 4, 7) ( 5, 7) ( 6, 7) ( 7, 7) ( 8, 7) ( 8, 6) ( 8, 5) ( 8, 4) ( 8, 3) ( 8, 2) ( 8, 1) ( 8, 0) ( 7, 0) ( 6, 0) ( 5, 0) ( 4, 0) ( 3, 0) ( 2, 0) ( 1, 0) ( 0, 0) ( 0, 1) ( 0, 2) ( 0, 3) ( 0, 4) ( 0, 5) ( 0, 6) ( 0, 7) ( 0, 8) ( 1, 8) ( 2, 8) ( 3, 8) ( 4, 8) ( 5, 8) ( 6, 8) ( 7, 8) ( 8, 8)