Submission #299495

#	Time	Username	Problem	Language	Result	Execution time	Memory
299495		user202729	Seats (IOI18_seats)	C++17	100 / 100	917 ms	106104 KiB

seats

// moreflags=grader.cpp
// ...
// I should have figure out this optimization earlier.
#include "seats.h"
#include<vector>
#include<climits>
#include<algorithm>
#if LOCAL
#include<iostream>
#else
#define NDEBUG
#endif
#include<cassert>

struct Tree{
	struct T{
		int minimum, count;
		T operator+(int lazy) const{return {minimum+lazy, count};}
		T operator+(T other) const{
			if(minimum<other.minimum) return *this;
			if(minimum>other.minimum) return other;
			return {minimum, count+other.count};
		}
	};
	struct Node{
		int lazy;
		T data_;
		T data() const{return data_+lazy;}
	};
	std::vector<Node> data;
	Tree(){}
	Tree(int number): data(number*2){
	}
	void build(){
		for(int node=int(data.size()/2); --node;)
			data[node].data_=data[node*2].data()+data[node*2+1].data();
	}

	// #fixed# note: initial state is inconsistent (counts values of nonleafs are 1)
	// (I knew that this will be problematic later...)

	void add(int left, int right, int value){
		if(left==right) return;
		assert(left<right);

		left+=int(data.size()/2); right+=int(data.size()/2);
		std::array<int, 2> const old{{left, right-1}};
		for(; left<right; left>>=1, right>>=1){
			if(left&1) data[left++].lazy+=value;
			if(right&1) data[--right].lazy+=value;
		}
		for(auto it: old){
			for(it>>=1; it; it>>=1){
				data[it].data_=data[it*2].data()+data[it*2+1].data();
			}
		}
	}

	int get(){
		// operator+ is commutative
		auto const d=data[1].data();
		assert(d.minimum>=4);
		return d.minimum==4 ? d.count: 0;
	}
};

struct MyData{
	MyData(){}

	//int width;
	std::vector<std::vector<int>> value; // pos -> time (in 0..H*W), with padded (H*W) values
	struct Pos{ int row, col; };
	std::vector<Pos> pos; // time -> pos
	Tree tree;

	template<int factor> void addTree_(Pos minimum, auto handler){
		auto const [r, c]=minimum;
		std::array<int, 4> times{{
			value[r][c],
			value[r+1][c],
			value[r][c+1],
			value[r+1][c+1],
		}};
		std::sort(begin(times), end(times));

		auto const TOP=int(tree.data.size()/2);
		assert(times[0]<TOP);     handler(times[0], factor);
		if(times[1]==TOP) return; handler(times[1], -factor);
		if(times[2]==TOP) return; handler(times[2], factor*5);
		if(times[3]==TOP) return; handler(times[3], -factor*5);
		// 5 is always greater than 4 => impossible
	}
	template<int factor> void addTreeMemory(Pos minimum){
		addTree_<factor>(minimum, [&](int a, int b){ freeMemory[a]+=b; });
	}
	template<int factor> void addTreeMemoryIndices(Pos minimum){
		addTree_<factor>(minimum, [&](int a, int b){ freeMemory[a]+=b; freeIndices.push_back(a); });
	}

	std::vector<int> freeMemory; // :)
	std::vector<int> freeIndices;

	MyData(int const H, int const W, std::vector<int> const& R_, std::vector<int> const& C_):
		value(H+2, std::vector<int>(W+2, H*W)),
		pos(H*W), tree(H*W), freeMemory(H*W)
	{
		for(int time=0; time<H*W; ++time){
			pos[time]={R_[time], C_[time]};
			value[R_[time]+1][C_[time]+1]=time;
		}

		for(int i=0; i<(int)value.size()-1; ++i)
			for(int j=0; j<(int)value[0].size()-1; ++j){
				addTreeMemory<1>({i, j});
			}
		int partial{};
		assert(freeMemory.size()==tree.data.size()/2);
		for(int a=0; a<(int)freeMemory.size(); ++a){
			partial+=freeMemory[a]; freeMemory[a]=0;
			tree.data[int(tree.data.size()/2)+a]={0, {partial, 1}};
		}
		tree.build();
	}

	int swap(int first, int sec){
		std::swap(pos[first], pos[sec]);

		std::array<std::array<int, 2> /* can be Pos too if it has comparison operators */, 8> minimums{{
			{pos[first].row, pos[first].col},
			{pos[first].row, pos[first].col+1},
			{pos[first].row+1, pos[first].col},
			{pos[first].row+1, pos[first].col+1},
			{pos[sec].row, pos[sec].col},
			{pos[sec].row, pos[sec].col+1},
			{pos[sec].row+1, pos[sec].col},
			{pos[sec].row+1, pos[sec].col+1},
		}};
		std::sort(begin(minimums), end(minimums));
		auto const last=std::unique(begin(minimums), end(minimums));

		std::for_each(minimums.begin(), last, [&](auto it){
			addTreeMemoryIndices<-1>({it[0], it[1]});
		});

		value[pos[first].row+1][pos[first].col+1]=first;
		value[pos[sec].row+1][pos[sec].col+1]=sec;

		std::for_each(minimums.begin(), last, [&](auto it){
			addTreeMemoryIndices<1>({it[0], it[1]});
		});

		for(auto a: freeIndices) if(auto& l=freeMemory[a]){
			tree.add(a, int(tree.data.size()/2), l);
			l=0;
		}
		freeIndices.clear();

		return tree.get();
	}
} myData;

void give_initial_chart(int H, int W, std::vector<int> R, std::vector<int> C) {
	myData=MyData{H, W, std::move(R), std::move(C)};
}

int swap_seats(int a, int b) {
	return myData.swap(a, b);
}

Compilation message (stderr)

seats.cpp:76:50: warning: use of 'auto' in parameter declaration only available with '-fconcepts'
   76 |  template<int factor> void addTree_(Pos minimum, auto handler){
      |                                                  ^~~~
seats.cpp: In member function 'void MyData::addTree_(MyData::Pos, auto:1)':
seats.cpp:88:3: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
   88 |   if(times[1]==TOP) return; handler(times[1], -factor);
      |   ^~
seats.cpp:88:29: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
   88 |   if(times[1]==TOP) return; handler(times[1], -factor);
      |                             ^~~~~~~
seats.cpp:89:3: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
   89 |   if(times[2]==TOP) return; handler(times[2], factor*5);
      |   ^~
seats.cpp:89:29: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
   89 |   if(times[2]==TOP) return; handler(times[2], factor*5);
      |                             ^~~~~~~
seats.cpp:90:3: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
   90 |   if(times[3]==TOP) return; handler(times[3], -factor*5);
      |   ^~
seats.cpp:90:29: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
   90 |   if(times[3]==TOP) return; handler(times[3], -factor*5);
      |                             ^~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 6 / 6
• Subtask 3: 20 / 20
• Subtask 4: 6 / 6
• Subtask 5: 33 / 33
• Subtask 6: 30 / 30