Submission #334298

#	Time	Username	Problem	Language	Result	Execution time	Memory
334298		nicholask	Arranging Shoes (IOI19_shoes)	C++14	100 / 100	94 ms	11240 KiB

shoes

#include "shoes.h"
#include <bits/stdc++.h>
using namespace std;
long long bit[200005];
void add(int x,int v){
	for (int i=x; i<200005; i+=(i&-i)) bit[i]+=v; 
}
int query(int x){
	int ans=0;
	for (int i=x; i; i-=(i&-i)) ans+=bit[i];
	return ans;
}
long long count_swaps(vector <int> s){
	int n=(s.size()>>1);
	long long ans=0;
	vector <pair <int,int> > shs[100001];
	vector <pair <int,int> > q;
	for (int i=0; i<n+n; i++) shs[abs(s[i])].push_back({s[i],i});
	for (int i=1; i<100001; i++){
		sort(shs[i].begin(),shs[i].end());
		int m=(shs[i].size()>>1);
		for (int j=0; j<m; j++){
			int ff=shs[i][j].second,ss=shs[i][j+m].second;
			if (ff>ss){
				swap(ff,ss);
				ans++;
			}
			q.push_back({ff+1,ss+1});
		}
	}
	sort(q.begin(),q.end());
	for (int i=1; i<=n+n; i++) add(i,1);
	for (auto&i:q){
		ans+=query(i.second-1)-query(i.first);
		add(i.first,-1);
		add(i.second,-1);
	}
	return ans;
}

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