Submission #30625

#	Time	Username	Problem	Language	Result	Execution time	Memory
30625		samir_droubi	Aliens (IOI16_aliens)	C++14	60 / 100	606 ms	136964 KiB

aliens

#include "aliens.h"
#include <bits/stdc++.h>
#define pii pair<int,int>
#define ll long long
using namespace std;
bool cmp(pii x , pii y)
{
	if(x.first == y.first)return x.second > y.second;
	return x.first < y.first;
}
struct CHT{
	vector<ll>m;
	vector<ll>p;
	int it=0;
	bool check()
	{
		if(m.size() < 3)return false;
		int l1 = m.size() - 3;
		int l2 = m.size() - 2;
		int l3 = m.size() - 1;
		return 1LL*(p[l3] - p[l1]) * (m[l1] - m[l2]) < 1LL*(p[l2] - p[l1]) * (m[l1] - m[l3]);
	}
	void add(ll M,ll P)
	{
		m.push_back(M);
		p.push_back(P);
		while(check())
		{
			m.erase(m.end() - 2);
			p.erase(p.end() - 2);
		}
	}
	ll calc(ll x,int i)
	{
		return x * m[i] + p[i];
	}
	ll query(ll x)
	{
		if(it >= m.size() )it = m.size() - 1;
		while(it < m.size() - 1 && calc(x , it) >= calc(x , it + 1 ) ){
			++it;
		}
		return calc(x , it);
	}
}ds[4005];
long long take_photos(int n, int m, int k, std::vector<int> r, std::vector<int> c) {
   	vector<pii>tmp;
   	vector<pii>v;
   	for(int i = 0 ; i < n ; ++i)
   		tmp.push_back( { min( r[i], c[i] ) , max( r[i] , c[i] ) } );
   	sort( tmp.begin() , tmp.end() , cmp );

   	int last = -1;
   	for(int i = 0 ; i < n ; ++i)
   	{
   		if(tmp[i].second <= last)continue;
   		v.push_back( tmp[i] );
   		last = max(last , tmp[i].second);
   	}

   	ll ans = (1LL <<61);

   	for(int i= 0 ; i <= k; ++i)
   		ds[i].add(-2LL * (v[0].first - 1) , 1LL*(v[0].first - 1) * (v[0].first - 1) );

   	n = v.size();
   	for(int i = 0 ; i < n ; ++i)
   	{
   		ll l = v[i].first;
   		ll r = v[i].second;
   		for(int j = k ;  j >= 1 ; --j)
   		{
   			ll dp = ds[j - 1].query(r) +  1LL*r * r;
   			if(i == n - 1)ans = min(ans , dp);
   			if(i < n - 1)
   			{
   				ll L = v[i + 1].first;
   				ll mx = max(0LL , r - L + 1);
				ds[j].add( -2 * (L - 1) , (L - 1) * (L - 1) + dp - mx * mx );
   			}
   		}
   	}
   	return ans;
}

Compilation message (stderr)

aliens.cpp: In member function 'long long int CHT::query(long long int)':
aliens.cpp:39:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if(it >= m.size() )it = m.size() - 1;
         ^
aliens.cpp:40:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   while(it < m.size() - 1 && calc(x , it) >= calc(x , it + 1 ) ){
            ^
aliens.cpp: In function 'long long int take_photos(int, int, int, std::vector<int>, std::vector<int>)':
aliens.cpp:69:9: warning: unused variable 'l' [-Wunused-variable]
      ll l = v[i].first;
         ^

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