[HaBo]

#include <stdio.h>

int next(int);
int buf[10]={0,0,0,0,0,0,0,0,0,0};

int main()
{
	int i;
	next(1);
	
	for(i=0;i<10;i++)
		printf("%d", buf[i]);
	printf("\n");
	return 0;
}

int next(int n)
{
	int p;
	if(n>5)
		return 1;
	for(p=0;p<10;p++)
	{
		if(p+n>=10)
			return 0;
		if(buf[p]==0&&buf[p+n]==0)
		{
			buf[p]=buf[p+n]=n;
			if(next(n+1))
				return 1;
			else
				buf[p]=buf[p+n]=0;
		}
	}
	return 0;
}

#include <iostream>
#include <algorithm>
using namespace std;

int main() {
    int n[] = {1, 2, 3, 4, 5};
    const int countPairs = 5;
    const int countDigits = 2*countPairs;
    int *a = new int[countDigits];

    for (int i = 0; i < countPairs; i++)
        a[i] = 0;

    do {
        int iAdd = 0;
        for (int i = 0; i < countPairs; i++) {
            while (a[i + iAdd] != 0 && i + iAdd < countDigits)
                iAdd += 1;
            if (i + iAdd >= countDigits || i + iAdd + n[i] >= countDigits)
                break;
            a[i + iAdd] = n[i];
            a[i + iAdd + n[i]] = n[i];
        }
        bool isResult = true;
        for (int i = countPairs; i < countDigits; i++) {
            if (a[i] == 0) {
                isResult = false;
                break;
            }
        }
        if (isResult) {
            for (int i = 0; i < countDigits; i++) {
                cout << a[i] << " ";
            }
            cout << endl;
        }
        for (int i = 0; i < countDigits; i++)
            a[i] = 0;
    } while (next_permutation(n, n+countPairs));
}