Submission #794564

#	Time	Username	Problem	Language	Result	Execution time	Memory
794564		Pablo_No	Arranging Shoes (IOI19_shoes)	C++17	100 / 100	88 ms	17992 KiB

shoes

#include "shoes.h"

#include <iostream>
#include <set>

using namespace std;

const int N = 1e5+5;

set<int> p[2*N];

int ft[2*N];

void add(int p, int v)
{
	while(p < 2*N)
	{
		ft[p] += v;

		p += (p & (-p));
	}
}

int rsq(int p)
{
	int ans = 0;
	while(p)
	{
		ans += ft[p];

		p -= (p & (-p));
	}
	return ans;
}

long long count_swaps(std::vector<int> s) {
	long long ans = 0;

	for(int i = 0; i < s.size(); i++)
	{
		int ai = s[i];
		if(!p[-ai+N].empty())
		{
			int fp = *p[-ai+N].begin();

			//cerr << rsq(fp+1) << '\n';

			ans += (i-fp)-(ai > 0)-rsq(fp+1);
			
			add(fp+2, 1);
			add(i+1, -1);

			p[-ai+N].erase(fp);
		}
		else
		{
			p[ai+N].insert(i);
		}
	}

	return ans;
}

Compilation message (stderr)

shoes.cpp: In function 'long long int count_swaps(std::vector<int>)':
shoes.cpp:39:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   39 |  for(int i = 0; i < s.size(); i++)
      |                 ~~^~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 20 / 20
• Subtask 3: 20 / 20
• Subtask 4: 15 / 15
• Subtask 5: 20 / 20
• Subtask 6: 15 / 15