参考答案：

#include<iostream>
#include<algorithm>
using namespace std;
const int N = 20;
struct node
{
    long long a;
    long long b;
    long long c;
};
bool cmp(struct node a1, struct node b1)
{
    return a1.c < b1.c;
}
int main()
{
    int n;
    cin >> n;
    struct node a[N];
    for (int i = 1; i <= n; ++i)
    {
        cin >> a[i].a >> a[i].b;
        a[i].c = a[i].a * a[i].a + a[i].b * a[i].b;
    }
    sort(a + 1, a + 1 + n, cmp);
    for (int i = 1; i <= n; ++i)
    {
        cout << a[i].a << ' ' << a[i].b << ' ' << a[i].c << endl;
    }

    return 0;
}