Parcurgere elemente in spirala

#include <iostream>

using namespace std;
int M[100][100];
int main()
{
    int nr=1, n,  i, j, aux;

    cin>>aux;
    n=aux;
    int prima_linie=1, prima_coloana=1;

    while(n!=0){
        for(j=prima_coloana; j<=n; j++){
        M[prima_linie][j]=nr;
        nr++;
    }

    for(i=2; i<=n; i++){
        M[i][n]=nr;
        nr++;
    }


    for(j=n-1; j>=prima_coloana; j--){
        M[n][j]=nr; nr++;
    }


    for(i=n-1; i>prima_linie; i--){
        M[i][prima_coloana]=nr;
        nr++;
    }
    n--;
    prima_linie++;
    prima_coloana++;
    }


    for(i=1; i<=aux; i++){
        for(j=1; j<=aux; j++)
            cout<<M[i][j]<<" ";
        cout<<endl;
    }

    return 0;
}