Submission #792023

#	Time	Username	Problem	Language	Result	Execution time	Memory
792023		APROHACK	Arranging Shoes (IOI19_shoes)	C++17	50 / 100	22 ms	9296 KiB

shoes

#include "shoes.h"
#include <bits/stdc++.h>
#define ll long long
#define ff first
#define ss second
#define pb push_back
using namespace std;
int nxt[100005][2];
bool past[100005] ;
int n;
int find_next(int k, int positive){
	if(!past[k])return k;
	if(!past[nxt[k][positive]])return nxt[k][positive];
	return nxt[k][positive] = find_next(nxt[k][positive], positive); // siempre tiene que existir.
}

int bit[100005];
void update(int pos, int val){
	pos ++ ;
	for(; pos <= n ; pos += pos&(-pos)){
		bit[pos] += val;
	}
}
ll query(int pos){
	ll ans = 0;
	pos ++ ;
	for(; pos > 0 ; pos -= pos&(-pos)){
		ans += bit[pos];
	}
	return ans;
}

ll getAns(int l, int r){

	if(l > r)return 0;
	if(l > 0)return query(r) - query(l-1);
	else return query(r);
}



long long count_swaps(std::vector<int> s) {
	n = s.size();
	for(int i = 0 ; i <=n+2 ; i ++)bit[i] = 0;
	int siguiente[n][2]; // 0 negative 1 positive
	for(int i = 0 ; i < n ; i ++)update(i, 1);
	for(int i = 1 ; i <= n ; i ++){
		siguiente[i][0] = -1;
		siguiente[i][1] = -1;
		nxt[i][0] = -1;
		nxt[i][1] = -1;
	}
	
	for(int i = n-1 ; i >= 0 ; i--){
		nxt[i][0] = siguiente[abs(s[i])][0];
		nxt[i][1] = siguiente[abs(s[i])][1];
		if(s[i] > 0)siguiente[abs(s[i])][1] = i;
		else siguiente[abs(s[i])][0] = i;
	}
	
	memset(past, false, sizeof past);
	ll ans = 0;
	for(int i = 0 ; i < n ; i ++){
		if(past[i] )continue;
		int busca = 1;
		if(s[i] > 0)busca = 0;
		//cout << "buscando para " << i ;
		int k = find_next(nxt[i][busca], busca);
		//cout << " desde " << k << endl;
		ans += getAns(i+1, k-1);
		//cout << "sumed " << getAns(i+1, k-1);
		if(busca == 0)ans ++;
		past[k] = true;
		past[i] = true;
		update(k, -1);
		update(i, -1);
	}
	
	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