#include<bits/stdc++.h>
//#pragma GCC optimize("O3")
//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("unroll-loops")
using namespace std;
#define f first
#define s second
#define ll long long
#define pb push_back
#define ld long double
const int N = 1e5 + 10, mod = 1e9 + 7, T = 2000 + 10;
const ld eps = 0.9, e = 2.7, minT = 0.00001;
mt19937 rnd(time(NULL));
int n;
vector<pair<int, int>> a, ans;
int res(vector<pair<int, int>> & a){
pair<int, int> was = {0, 0}, last = {0, 0};
vector<pair<int, int>> res;
for(int i = 0; i < n; ++i){
pair<int, int> now = {a[i].f - last.f, a[i].s - last.s};
if(now.f * was.f > 0){
res.pb({a[i].f, last.s});
was = {0, now.s};
}else if(now.s * was.s > 0){
res.pb({last.f, a[i].s});
was = {now.f, 0};
}else{
if(last.f != 0 || last.s != 0)
res.pb(last);
pair<int, int> nxt = {a[i + 1].f - a[i].f, a[i + 1].s - a[i].s};
if(nxt.f * now.f > 0){
res.pb({last.f, a[i].s});
was = {now.f, 0};
}else{
res.pb({a[i].f, last.s});
was = {0, now.s};
}
}
last = a[i];
}
res.pb(a[n - 1]);
if(res.size() < ans.size() || ans.empty())
ans = res;
return res.size();
}
bool chance(ld c){
int maxn = 1000000;
ld num = (ld)(rnd() % maxn) / (maxn - 1);
return num <= c;
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
// freopen("08.in", "r", stdin);
// freopen("08.txt", "w", stdout);
cin >> n;
a.resize(n);
for(int i = 0; i < n; ++i)
cin >> a[i].f >> a[i].s;
sort(a.begin(), a.end());
int now = res(a);
ld t = T;
while(t > minT){
// cout << t << endl;
int l = rnd() % n;
int r = rnd() % n;
swap(a[l], a[r]);
int nres = res(a);
if(nres < now || !chance(pow(e, (nres - now) / t)))
swap(a[l], a[r]);
t *= eps;
}
cout << ans.size() << "\n";
for(auto v : ans)
cout << v.f << " " << v.s << endl;
}
Compilation message
/usr/bin/ld: /tmp/ccjFkFYs.o: in function `main':
grader.cpp:(.text.startup+0x0): multiple definition of `main'; /tmp/ccRQuLPv.o:vision.cpp:(.text.startup+0x0): first defined here
/usr/bin/ld: /tmp/ccjFkFYs.o: in function `main':
grader.cpp:(.text.startup+0x1b3): undefined reference to `construct_network(int, int, int)'
collect2: error: ld returned 1 exit status
