Submission #286640

#	Time	Username	Problem	Language	Result	Execution time	Memory
286640		user202729	Wiring (IOI17_wiring)	C++17	100 / 100	63 ms	8696 KiB

wiring

// moreflags=grader.cpp
//
// 13
// :(
#include "wiring.h"
#include<vector>
#if not LOCAL
#define NDEBUG
#endif
#include<cassert>
#include<climits>
#include<cstdint>
#include<algorithm>


struct Point{
	bool red; int pos;
	bool operator<(Point other) const{return pos<other.pos;}
};
template<bool type> struct Iterator
{
	using B=std::iterator<std::forward_iterator_tag, Point>;
#define F(N) using N=typename B::N
	F(iterator_category);
	F(value_type);
	F(difference_type);
	F(pointer);
	F(reference);
#undef F

	std::vector<int>::iterator iterator;
#define F(op) bool operator op (Iterator other) const{return iterator op other.iterator;}
	//F(<) F(>) 
	F(==) F(!=)
#undef F

	Iterator& operator++(){ ++iterator; return *this; }
	Point operator*() const{return {type, *iterator};}
}; // rust is nicer than this...

long long min_total_length(std::vector<int> red, std::vector<int> blue) {
	std::vector<Point> points;
	points.reserve(red.size()+blue.size());
	std::merge(
			Iterator<true>{red.begin()},
			Iterator<true>{red.end()},
			Iterator<false>{blue.begin()},
			Iterator<false>{blue.end()},
			std::back_inserter(points));
	assert(points.size()==red.size()+blue.size());

	std::vector<int64_t> sumSuffix(points.size()+1);
	for(auto [last, index]=std::pair((int64_t)0, points.size()); index--;){
		sumSuffix[index]=last+=points[index].pos;
	}
	// std::partial_sum
	
	std::vector<int64_t> result(points.size()+1, INT64_MAX);
	result[0]=0;

	auto const groupEnd=[&](int index){
		int result=index;
		while(result<(int)points.size() and points[result].red==points[index].red) ++result;
		return result;
	};
	int last=-1, next=groupEnd(0), next2=groupEnd(next);
	for(int index=0; index<(int)points.size(); ++index){
		if(index==next){
			last=index-1;
			next=next2; next2=groupEnd(next2);
		}
		auto const curResult=result[index];
		if(last>=0)
			result[index+1]=std::min(result[index+1], curResult+points[index].pos-points[last].pos);
		if(next<(int)points.size())
			result[index+1]=std::min(result[index+1], curResult+points[next].pos-points[index].pos);
		if(auto const block=next-index; next2-next>=block)
			result[next+block]=std::min(result[next+block], curResult
					+(sumSuffix[next]-sumSuffix[next+block])
					-(sumSuffix[index]-sumSuffix[next])
					);
	}

	return result[points.size()];
}

• Subtask 1: 7 / 7
• Subtask 2: 13 / 13
• Subtask 3: 10 / 10
• Subtask 4: 25 / 25
• Subtask 5: 45 / 45