Submission #44379

#	Time	Username	Problem	Language	Result	Execution time	Memory
44379		szawinis	Aliens (IOI16_aliens)	C++17	0 / 100	2 ms	784 KiB

aliens

#include "aliens.h"
#include <bits/stdc++.h>
using ll = long long;
using namespace std;

inline ll square(ll x) { return x*x; }

void tidy_up(int &n, vector<int> &l, vector<int> &r) {
	for(int i = 0; i < n; i++) if(l[i] > r[i]) swap(l[i], r[i]);
	vector<int> id(n);
	iota(id.begin(), id.end(), 0);
	sort(id.begin(), id.end(), [l, r] (int i, int j) {
		return make_pair(r[i], -l[i]) < make_pair(r[j], -l[j]);
	});
	vector<int> tmp;
	tmp.push_back(-1);
	tmp.push_back(id[0]);
	for(int i = 1; i < n; i++) {
		while(tmp.size() > 1 && l[tmp.back()] >= l[id[i]]) tmp.pop_back();
		tmp.push_back(id[i]);
	}
	n = tmp.size() - 1;
	id = tmp;
	for(int i = 1; i <= n; i++) tmp[i] = r[id[i]];
	r = tmp;
	for(int i = 1; i <= n; i++) tmp[i] = l[id[i]];
	l = tmp;
}
const ll is_query = -(1ll << 62);
struct line {
	ll m, c;
	mutable function<const line*()> succ;
	bool operator<(const line& rhs) const {
		if(rhs.c != is_query) return m > rhs.m;
		const line* s = succ();
		if(!s) return false;
		return (s->m - m < 0) ^ (c - s->c < (double) (s->m - m)*rhs.m);
	}
};
class MinHull : public multiset<line> {
	bool bad(iterator it) {
		auto nxt = next(it);
		if(it == begin()) {
			if(nxt != end()) return nxt->m == it->m && nxt->c <= it->c;
			else return false;
		}
		auto pre = prev(it);
		if(nxt == end()) return pre->m == it->m && pre->c <= it->c;
		line l1 = *pre, l2 = *it, l3 = *nxt;
		assert(l1.m >= l2.m && l2.m >= l3.m && l1.m >= l3.m);
		return (double) (l3.c-l1.c)*(l1.m-l2.m) <= (double) (l2.c-l1.c)*(l1.m-l3.m);
	}
public:
	void update(ll m, ll c) {
		auto it = insert((line) {m, c});
		it->succ = [=] { return next(it) == end() ? 0 : &*next(it); };
		if(bad(it)) {
			erase(it);
			return;
		}
		while(it != begin() && bad(prev(it))) erase(prev(it));
		while(next(it) != end() && bad(next(it))) erase(next(it));
	}
	ll query(ll x) {
		auto it = lower_bound((line) {x, is_query});
		assert(it != end());
		return it->m*x + it->c;
	}
} hull;
// struct cht {
// 	struct line {
// 		ll m, c;
// 		line(ll m, ll c): m(m), c(c) {};
// 		ll getVal(ll x) { return m*x + c; }
// 	};
// 	vector<line> f;
// 	bool bad(line l1, line l2, line l3) { // m1 > m2 > m3
// 		return (double) (l1.c-l3.c)*(l2.m-l1.m) <= (double) (l1.c-l2.c)*(l3.m-l1.m);
// 	}
// 	void insert(ll m, ll c) {
// 		line l = line(m, c);
// 		while(f.size() >= 2 && bad(f[f.size()-2], f[f.size()-1], l)) f.pop_back();
// 		f.push_back(l);
// 	}
// 	ll query(ll x) {
// 		static int idx = 0;
// 		while(idx+1 < f.size() && f[idx+1].getVal(x) < f[idx].getVal(x)) ++idx;
// 		return f[idx].getVal(x);
// 	}
// 	void clear() { f.clear(); }
// } hull;

vector<vector<ll> > dp;

ll take_photos(int n, int m, int k, vector<int> l, vector<int> r) {
	tidy_up(n, l, r);
	dp = vector<vector<ll> >(k+1, vector<ll>(n+1, -1));
	hull.update(-2*(l[1]-1), square(l[1]-1));
	for(int j = 1; j <= k; j++) {
		dp[j][0] = 0;
		for(int i = 1; i <= n; i++) {
			dp[j][i] = hull.query(r[i]) + square(r[i]);
		}
		hull.clear();
		for(int i = 1; i < n; i++) {
			hull.update(-2*(l[i+1]-1), square(l[i+1]-1) + dp[j][i] - square(max(0, r[i] - l[i+1] + 1)));
		}
	}
	return dp[k][n];
}

• Subtask 1: 0 / 4
• Subtask 2: 0 / 12
• Subtask 3: 0 / 9
• Subtask 4: 0 / 16
• Subtask 5: 0 / 19
• Subtask 6: 0 / 40