Submission #724230

#	Time	Username	Problem	Language	Result	Execution time	Memory
724230		badont	Arranging Shoes (IOI19_shoes)	C++17	45 / 100	47 ms	13992 KiB

shoes

#include "shoes.h"
#include <cmath>
#include <cstdlib> 
#include <cassert>

long long count_swaps(std::vector<int> s) {
	using ll = long long;
	using namespace std;
	ll n = (int)s.size(); n /= 2;	

	vector<vector<ll>> pos(n, vector<ll>()), neg(n, vector<ll>());	

	for (int i = 0; i < 2 * n; i++) {
		ll x = abs(s[i]);
		if (s[i] < 0) {
			neg[x - 1].push_back(i);
		} else {
			pos[x - 1].push_back(i);
		}
	}

	ll op_1 = 0, op_2 = 0;
	for (int i = 0; i < n; i++) {
		assert(neg[i].size() == pos[i].size());
		for (int j = 0; j < (int)neg[i].size(); j++) {
			int x = neg[i][j], y = pos[i][j];
			op_1 += abs(x - y) - 1;
			if (x > y) op_2++;
		}
	}

	op_1 /= 2;

	return op_1 + op_2;
}

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