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| #include <cstdio>
#include <vector>
#include <utility>
#include <cassert>
#include <cstdlib>
#include <fstream>
#include <iostream>
#include <algorithm>
#define hb bh
using namespace std;
const int maxn = 1000000;
int n, m, seed;
int bh[maxn];
vector<pair<int, int> > ve;
vector<int> rt;
vector<int> ln;
int main(int argc, char** argv) {
assert(argc == 4);
ofstream fout(argv[1]);
sscanf(argv[2], "%d", &n);
sscanf(argv[3], "%d", &seed);
srand((unsigned) seed);
fout << n << '\n';
mt19937 rnd((unsigned) seed);
int lim = n / 3;
for (int i = 1; i <= n; ++i) {
bh[i] = i;
}
int Lrt = max(1, max(lim - (lim / 10), lim - 10));
random_shuffle(bh + 1, bh + n + 1);
rt.push_back(bh[1]);
for (int i = 2; i <= lim; ++i) {
ve.push_back(make_pair(bh[i], rt[rnd() % rt.size()]));
if (i - Lrt > 1) {
rt.push_back(hb[i - Lrt]);
}
}
for (int i = lim + 1; i <= n; ++i) {
if (ln.empty() || !(rnd() % max(3, lim >> 3))) {
ve.push_back(make_pair(hb[i], rt[rnd() % rt.size()]));
} else {
ve.push_back(make_pair(hb[i], ln[max(0, (int) (ln.size() - (rnd() % 100) - 1))]));
}
ln.push_back(hb[i]);
}
random_shuffle(ve.begin(), ve.end());
for (auto x : ve) {
if (rnd() & 1) {
fout << x.first << ' ' << x.second << '\n';
} else {
fout << x.second << ' ' << x.first << '\n';
}
}
fout.close();
return 0;
}
|
