题解

#include <bits/stdc++.h>
using namespace std;

int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);

for (int n = 2; n <= 40; ++n) {
    vector<tuple<int, int, int>> edges; 
    for (int i = 1; i <= n; ++i) {
        for (int j = i + 1; j <= n; ++j) {
            int d = min(j - i, n - (j - i));
            edges.emplace_back(d, i, j);
        }
    }
    sort(edges.begin(), edges.end());
    for (auto &[d, i, j] : edges) {
        cout << i << ' ' << j << '\n';
    }
}
return 0;

}