Submission #337644

#	Time	Username	Problem	Language	Result	Execution time	Memory
337644		errorgorn	Aliens (IOI16_aliens)	C++17	100 / 100	271 ms	8172 KiB

aliens

//雪花飄飄北風嘯嘯
//天地一片蒼茫

#include "aliens.h"
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>
using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
#define ll long long
#define ii pair<ll,ll>
#define iii pair<ii,ll>
#define fi first
#define se second
#define endl '\n'
#define debug(x) cout << #x << " is " << x << endl

#define rep(x,start,end) for(auto x=(start)-((start)>(end));x!=(end)-((start)>(end));((start)<(end)?x++:x--))
#define all(x) (x).begin(),(x).end()
#define sz(x) (int)(x).size()

#define indexed_set tree<ll,null_type,less<ll>,rb_tree_tag,tree_order_statistics_node_update>
//change less to less_equal for non distinct pbds, but erase will bug

mt19937 rng(chrono::system_clock::now().time_since_epoch().count());

int n,m,k;
vector<ii> v;
ll extra[100005];

ll sq(ll i){return i*i;}

struct line{
	ll m,c,g;
	
	ii eval(ll x){
		return ii(m*x+c,g);
	}
};

struct hull{
	deque<line> dq;
	
	double POI(line i,line j){
		return (long double)(i.c-j.c)/(j.m-i.m);
	}
	
	void add(line i){
		while (sz(dq)>=2 && POI(dq.back(),i)<=POI(dq[sz(dq)-2],dq.back())) dq.pop_back();
		dq.push_back(i);
	}
	
	ii query(ll i){
		while (sz(dq)>=2 && dq[1].eval(i).fi<dq[0].eval(i).fi) dq.pop_front();
		return dq.front().eval(i);
	}
};

ii param(ll lambda){
	hull h;
	ii val=ii(0,0);
	rep(x,0,sz(v)){
		h.add({-2*v[x].fi,val.fi-extra[x]+sq(v[x].fi)+lambda,val.se});
		val=h.query(v[x].se);
		val.se++;
		val.fi+=sq(v[x].se);
	}
	
	return val;
}

long long take_photos(int N, int M, int K, std::vector<int> R, std::vector<int> C) {
    n=N,m=M,k=K;
    
    
    rep(x,0,n){
		int a=R[x],b=C[x];
		if (a>b) swap(a,b);
		v.push_back(ii(a,b+1));
	}
	
	sort(all(v),[](ii i,ii j){
		if (i.fi!=j.fi) return i.fi<j.fi;
		else return i.se>j.se;
	});
	
	vector<ii> temp;
	for (auto &it:v){
		if (temp.empty() || temp.back().se<it.se) temp.push_back(it);
	}
	
	swap(v,temp);
	
	//for (auto &it:v) cout<<it.fi<<" "<<it.se<<endl;
	
	rep(x,1,sz(v)) extra[x]=sq(max(0LL,v[x-1].se-v[x].fi));
	//rep(x,0,sz(v)) cout<<extra[x]<<" "; cout<<endl;
	
	k=min(k,sz(v));
	ll lo=0,hi=1e12,mi;
	//lo>=k, k>hi
	
	while (hi-lo>1){
		mi=hi+lo>>1;
		
		if (param(mi).se>=k) lo=mi;
		else hi=mi;
	}
	
	auto val=param(lo);
	return val.fi-val.se*lo+(val.se-k)*hi;
}

Compilation message (stderr)

aliens.cpp: In function 'long long int take_photos(int, int, int, std::vector<int>, std::vector<int>)':
aliens.cpp:106:8: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  106 |   mi=hi+lo>>1;
      |      ~~^~~

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