Submission #136447

#	Time	Username	Problem	Language	Result	Execution time	Memory
136447		ckodser	Aliens (IOI16_aliens)	C++14	100 / 100	810 ms	30336 KiB

aliens

#include "aliens.h"
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <locale>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <typeinfo>
#include <utility>
#include <valarray>
#include <vector>
#if __cplusplus >= 201103L
#include <array>
#include <atomic>
#include <chrono>
#include <condition_variable>
#include <forward_list>
#include <future>
#include <initializer_list>
#include <mutex>
#include <random>
#include <ratio>
#include <regex>
#include <scoped_allocator>
#include <system_error>
#include <thread>
#include <tuple>
#include <typeindex>
#include <type_traits>
#include <unordered_map>
#include <unordered_set>
#endif
#define ll long long
#define pb push_back
#define mp make_pair
#define ld long double
#define F first
#define S second
#define pii pair<ll,ll>
#define pdd pair<ld,ld> 

using namespace :: std;
 
const ll maxn=3e5+500;;
const ll inf=1e12+900;
ld tav2(ld x){return x*x;}
 

vector<pair<pdd,ll> > khat;
vector<pair<ld,ll> > cht;
ll poi;
 
ld barkhord(ll a,ll b){
	return (khat[a].F.F-khat[b].F.F)/(khat[b].F.S-khat[a].F.S);
}
void clearr(){
	poi=0;
	khat.clear();
	cht.clear();
}
void add(ld x,ld v,ll h){
	khat.pb(mp(mp(x,v),h));
	ll i=khat.size()-1;
	while(cht.size() && barkhord(cht.back().S,i)<=cht.back().F)cht.pop_back();
	if(cht.empty()){
		cht.pb(mp(0,i));
	}else{
		cht.pb(mp(barkhord(cht.back().S,i),i));
	}
}
pair<ld,ll>  findMinAt(ld t){
	if(cht.size()<=1)poi=0;
	else poi=min(poi,(ll)cht.size()-2);
	
	while(poi<cht.size()-1 && cht[poi+1].F<=t)poi++;
	ll v=cht[poi].S;
	return mp(khat[v].F.F+khat[v].F.S*t,khat[v].S);
}
 
vector<pii> vec;
 
 
ll X[maxn];
ll V[maxn];
const ll maxm=1e6+100;
 
ll mx[maxm];
 
ll cnt[maxn];
ld dp[maxn];
pair<ld,ll> solve(vector<pii> vec,ld mid){
	clearr();
	add(X[0],V[0],0);
	for(ll i=0;i<vec.size();i++){
		pair<ld,ll> e=findMinAt(vec[i].F);
		dp[i]=e.F+tav2(vec[i].F)+mid;
		cnt[i]=e.S+1;
		add(X[i+1]+dp[i],V[i+1],cnt[i]);
	}
	return mp(dp[vec.size()-1],cnt[vec.size()-1]);
}
long long take_photos(int n, int m, int k, vector<int> r, vector<int> c) {
	swap(n,m);
	fill(mx,mx+maxm,inf);
 
	for(ll i=0;i<m;i++){
		if(c[i]>r[i]){
			swap(c[i],r[i]);
		}
		mx[r[i]]=min(mx[r[i]],(ll)c[i]);
	}
	stack<ll> stk;
	for(ll i=0;i<n;i++){
		while(stk.size() && mx[stk.top()]>=mx[i]){
			stk.pop();
		}
		if(mx[i]!=inf){
			stk.push(i);
		}	
	}
	while(stk.size()){
		vec.pb(mp(stk.top(),mx[stk.top()]));
		stk.pop();
	}
	sort(vec.begin(),vec.end());
 
	X[0]=tav2(vec[0].S);
	V[0]=vec[0].S*-2;
	for(ll i=0;i+1<vec.size();i++){
		X[i+1]=-tav2(max((ll)0,vec[i].F-vec[i+1].S+1))+tav2(vec[i+1].S);
		V[i+1]=vec[i+1].S*-2;
	}
	for(ll i=0;i<vec.size();i++){
		vec[i].F++;
	}
	ld b=0;
	ld e=1e13;
	for(ll i=0;i<100;i++){
		ld mid=(e+b)/2;
		pair<ld,ll> r=solve(vec,mid);
		if(r.S<=k){
			e=mid;	
		}else{
			b=mid;	
		}
	}
	pair<ld,ll> rr=solve(vec,e);
	return round(rr.F-k*e);
}

Compilation message (stderr)

aliens.cpp: In function 'std::pair<long double, long long int> findMinAt(long double)':
aliens.cpp:97:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  while(poi<cht.size()-1 && cht[poi+1].F<=t)poi++;
        ~~~^~~~~~~~~~~~~
aliens.cpp: In function 'std::pair<long double, long long int> solve(std::vector<std::pair<long long int, long long int> >, long double)':
aliens.cpp:116:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(ll i=0;i<vec.size();i++){
             ~^~~~~~~~~~~
aliens.cpp: In function 'long long int take_photos(int, int, int, std::vector<int>, std::vector<int>)':
aliens.cpp:151:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(ll i=0;i+1<vec.size();i++){
             ~~~^~~~~~~~~~~
aliens.cpp:155:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(ll i=0;i<vec.size();i++){
             ~^~~~~~~~~~~

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