Submission #831945

#	Time	Username	Problem	Language	Result	Execution time	Memory
831945		DarkMatter	Lightning Rod (NOI18_lightningrod)	C++14	23 / 100	1529 ms	262144 KiB

Main

#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
#include<unordered_map>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef pair<int, int>pi;
typedef pair<ll, ll>pl;
typedef vector<pi>vpi;
typedef vector<pl>vpl;
typedef vector<vi> vvi;
typedef vector<vl> vvl;
typedef vector<string> vs;
typedef vector<bool> vb;
const long double PI = acos(-1);
const ll oo = 1e18;
const int MOD = 1e9 + 7;
const int N = 2e5 + 7;
#define endl '\n'
#define all(v) (v).begin(),(v).end()
#define rall(v) (v).rbegin(),(v).rend()
#define read(v) for (auto& it : v) scanf("%d", &it);
#define readL(v) for (auto& it : v) scanf("%lld", &it);
#define print(v) for (auto it : v) printf("%d ", it); puts("");
#define printL(v) for (auto it : v) printf("%lld ", it); puts("");
ll n;
vpl v;
ll ans = oo;
void calc(ll idx, vpl cur) {
	if (idx == n) {
		vb vis(n, false);
		for (int i = 0; i < cur.size(); i++) {
			for (int j = 0; j < n; j++) {
				if (vis[j])
					continue;
				if (abs(cur[i].first - v[j].first) <= (cur[i].second - v[j].second))
					vis[j] = true;
			}
		}
		sort(all(vis));
		if (vis[0])
			ans = min(ans, (ll)cur.size());
		return;
	}
	calc(idx + 1, cur);
	cur.push_back(v[idx]);
	calc(idx + 1, cur);
}
void solve() {
	scanf("%lld", &n);
	v.resize(n);
	ans = oo;
	bool ok = true;
	for (auto& it : v) {
		scanf("%lld %lld", &it.first, &it.second);
		if (it.second != 1)
			ok = false;
	}
	if (ok) {
		cout << n << endl;
		return;
	}
	if (n <= 20) {
		vpl cur;
		calc(0, cur);
		printf("%lld\n", ans);
		return;
	}
	vpl newV;
	for (auto& it : v)
		newV.push_back({ it.second,it.first });
	sort(all(newV), greater<pl>());
	v = newV;
	ans = 0;
	for (int i = 0; i < n; i++) {
		bool ok = true;
		for (int j = 0; j < i; j++)
			ok &= (abs(v[i].second - v[j].second) > (v[i].first - v[j].first));
		ans += ok;
	}
	printf("%lld\n", ans);
}
int t = 1;
int main() {
	//#ifndef ONLINE_JUDGE
	//	freopen("input.txt", "r", stdin);
	//#endif
		//scanf("%d", &t);
	while (t--) solve();
}

Compilation message (stderr)

lightningrod.cpp: In function 'void calc(ll, vpl)':
lightningrod.cpp:34:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   34 |   for (int i = 0; i < cur.size(); i++) {
      |                   ~~^~~~~~~~~~~~
lightningrod.cpp: In function 'void solve()':
lightningrod.cpp:52:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   52 |  scanf("%lld", &n);
      |  ~~~~~^~~~~~~~~~~~
lightningrod.cpp:57:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   57 |   scanf("%lld %lld", &it.first, &it.second);
      |   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 4 / 4
• Subtask 2: 7 / 7
• Subtask 3: 12 / 12
• Subtask 4: 0 / 21
• Subtask 5: 0 / 26
• Subtask 6: 0 / 10
• Subtask 7: 0 / 20