#include <vector>
#include <iostream>
 
using V=std::vector<int>;void s(std::vector<V>&m,V&v,int n,int h){int r=h,c=h,i=0,j,l=n-2*h-1;if(l>-1){do{v.push_back(m[r][c]);l?(j=i/l)<1?c++:j<2?r++:j<3?c--:r--:l;}while(++i<4*l);s(m,v,n,h+1);}}
 
std::vector<V> x{{1, 2, 3, 4}, {12, 13, 14, 5}, {11, 16, 15, 6}, {10, 9, 8, 7}};
std::vector<V> y{{1, 2, 3}, {8, 9, 4}, {7, 6, 5}};
std::vector<V> z;
 
int main()
{
    V v, w, t;
    s(x, v, x.size(), 0);
    for (auto i : v) std::cout << i << " ";
    std::cout << "\n";
    s(y, w, y.size(), 0);
    for (auto i : w) std::cout << i << " ";
    std::cout << "\n";
    s(z, t, z.size(), 0);
    for (auto i : t) std::cout << i << " ";
    std::cout << "\n";
}
 
 

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