Submission #411390

#	Time	Username	Problem	Language	Result	Execution time	Memory
411390		pliam	Arranging Shoes (IOI19_shoes)	C++14	50 / 100	299 ms	49104 KiB

shoes

#include "shoes.h"
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define MAXN 100005

int N;
map<int,vector<int>> emf;
int resp[MAXN];//start position of respective pair
bool used[MAXN];
int bit[MAXN];
ll ans;

int lsone(int x){
	return x&(-x);
}

void update(int pos){
	pos++;
	for(int x=pos;x<=N;x+=lsone(x)){
		bit[x]++;
	}
}

int query(int pos){
	pos++;
	int res=0;
	for(int x=pos;x>0;x-=lsone(x)){
		res+=bit[x];
	}
	return res;
}

long long count_swaps(std::vector<int> s) {
	N=s.size();
	for(int i=N-1;i>=0;i--){
		emf[s[i]].push_back(i);
	}
	for(int i=0;i<N;i++){
		if(used[i]) continue;

		resp[i]=emf[-s[i]].back();
		emf[-s[i]].pop_back();
		emf[s[i]].pop_back();
		used[i]=true;
		used[resp[i]]=true;
	}
	memset(used,false,sizeof(used));
	for(int i=0;i<N;i++){
		if(used[i]) continue;

		ll pos1=i-query(i-1);
		ll pos2=resp[i]-query(resp[i]-1);
		ans+=(pos2-pos1+((s[i]<0)?-1:0));

		update(i);
		update(resp[i]);
		used[i]=true;
		used[resp[i]]=true;
	}
	return ans;
}

• Subtask 1: 10 / 10
• Subtask 2: 20 / 20
• Subtask 3: 0 / 20
• Subtask 4: 0 / 15
• Subtask 5: 20 / 20
• Subtask 6: 0 / 15