Submission #620443

#	Time	Username	Problem	Language	Result	Execution time	Memory
620443		cheissmart	Arranging Shoes (IOI19_shoes)	C++14	100 / 100	93 ms	16676 KiB

shoes

#include "shoes.h"
#include <bits/stdc++.h>
#define IO_OP ios::sync_with_stdio(0), cin.tie(0)
#define F first
#define S second
#define V vector
#define PB push_back
#define EB emplace_back
#define MP make_pair
#define SZ(v) int((v).size())
#define ALL(v) (v).begin(), (v).end()

using namespace std;

typedef long long ll;
typedef pair<int, int> pi;
typedef V<int> vi;

const int INF = 1e9 + 7, N = 2e5 + 7;

int bit[N];

void add(int pos, int val) {
	for(; pos < N; pos += pos & -pos)
		bit[pos] += val;
}

int qry(int pos) {
	int res = 0;
	for(; pos; pos -= pos & -pos)
		res += bit[pos];
	return res;
}

ll count_swaps(vi s) {
	int n = SZ(s) / 2;
	V<vi> posl(n);
	V<vi> posr(n);
	for(int i = 0; i < n * 2; i++) {
		if(s[i] < 0) {
			posl[-s[i] - 1].PB(i);
		} else {
			posr[s[i] - 1].PB(i);
		}
	}
	ll ans = 0;
	V<pi> aux;
	for(int i = 0; i < n; i++) {
		assert(SZ(posl[i]) == SZ(posr[i]));
		for(int j = 0; j < SZ(posl[i]); j++) {
			if(posl[i][j] > posr[i][j]) {
				ans++;
				swap(posl[i][j], posr[i][j]);
			}
			aux.EB(posl[i][j], posr[i][j]);
		}
	}
	sort(ALL(aux));
	assert(SZ(aux) == n);
	vi p(2 * n);
	for(int i = 0; i < n; i++) {
		p[aux[i].F] = i * 2 + 1;
		p[aux[i].S] = i * 2 + 2;
	}
	for(int i = 2 * n - 1; i >= 0; i--) {
		ans += qry(p[i]);
		add(p[i], 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