Submission #837886

#	Time	Username	Problem	Language	Result	Execution time	Memory
837886		DarkMatter	Arranging Shoes (IOI19_shoes)	C++17	50 / 100	1097 ms	2668 KiB

shoes

#include<bits/stdc++.h>
#include "shoes.h"

using namespace std;

long long count_swaps(std::vector<int> v) {
	int n = v.size();
	bool ok = true;
	for (int i = 0; i < n / 2; i++) {
		if (v[i] > 0 || v[i] != v[i + (n / 2)]) {
			ok = false;
			break;
		}
	}
	for (int i = n / 2; i < n; i++) {
		if (v[i] < 0) {
			ok = false;
			break;
		}
	}
	if (ok) {
		n /= 2;
		long long ans = 0;
		for (int i = 0; i < n; i++)
			ans += i;
		return ans;
	}
	vector<bool>vis(n, false);
	long long ans = 0;
	vector<int>idx(n);
	iota(idx.begin(), idx.end(), 0);
	for (int i = 0; i < n; i++) {
		if (vis[i] || (idx[i] & 1 && v[i] > 0))
			continue;
		vis[i] = true;
		for (int j = i + 1; j < n; j++) {
			if (!vis[j] && v[j] == -v[i]) {
				vis[j] = true;
				int dif = idx[j] - idx[i] - 1;
				if (idx[i] % 2 == 0 && v[i] < 0)
					ans += dif;
				else
					ans += dif + 1;
				break;
			}
			idx[j]++;
		}
	}
	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