Submission #341757

#	Time	Username	Problem	Language	Result	Execution time	Memory
341757		ogibogi2004	Arranging Shoes (IOI19_shoes)	C++14	100 / 100	101 ms	19820 KiB

shoes

#include<bits/stdc++.h>
using namespace std;
#define ll long long
const int MAXN=2e5+6;
int fen[MAXN];
void update(int idx,int val)
{
	idx++;
	for(;idx<MAXN;idx+=idx&(-idx))
	{
		fen[idx]+=val;
	}
}
int query(int idx)
{
	idx++;
	int ret=0;
	for(;idx>0;idx-=idx&(-idx))
	{
		ret+=fen[idx];
	}
	return ret;
}
vector<int>shoes[MAXN][2];
bool vis[MAXN];
long long count_swaps(vector<int> s) {
	for(int i=0;i<s.size();++i)
	{
		if(s[i]>0)shoes[s[i]][0].push_back(i);
		else shoes[-s[i]][1].push_back(i);
	}
	for(int i=0;i<MAXN;i++)
	{
		reverse(shoes[i][0].begin(),shoes[i][0].end());
		reverse(shoes[i][1].begin(),shoes[i][1].end());
	}
	for(int i=0;i<s.size();++i)
	{
		update(i,+1);
	}
	ll ans=0;
	for(int i=0;i<s.size();++i)
	{
		if(vis[i])continue;
		if(s[i]<0)
		{
			int k=shoes[-s[i]][0].back();
			ans+=(ll)query(k)-query(i)-1;
			update(i,+1);
			vis[k]=1;
			update(k+1,-1);
			shoes[-s[i]][0].pop_back();
			shoes[-s[i]][1].pop_back();
		}
		else
		{
			int k=shoes[s[i]][1].back();
			ans+=(ll)query(k)-query(i);
			update(i,+1);
			update(k+1,-1);
			vis[k]=1;
			shoes[s[i]][1].pop_back();
			shoes[s[i]][0].pop_back();
		}
	}
	return ans;
}

Compilation message (stderr)

shoes.cpp: In function 'long long int count_swaps(std::vector<int>)':
shoes.cpp:27:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   27 |  for(int i=0;i<s.size();++i)
      |              ~^~~~~~~~~
shoes.cpp:37:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   37 |  for(int i=0;i<s.size();++i)
      |              ~^~~~~~~~~
shoes.cpp:42:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   42 |  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