Submission #415685

#	Time	Username	Problem	Language	Result	Execution time	Memory
415685		Mlxa	Arranging Shoes (IOI19_shoes)	C++14	50 / 100	1094 ms	26116 KiB

shoes

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define all(x) x.begin(), x.end()
#define mp make_pair
#define mt make_tuple
#define x first
#define y second
#include "shoes.h"

ll count_swaps(vector<int> s) {
	map<int, vector<int>> open, close;
	vector<pair<int, int>> pairs;
	for (int i = 0; i < (int)s.size(); ++i) {
		if (s[i] < 0) {
			open[abs(s[i])].push_back(i);
		} else {
			close[abs(s[i])].push_back(i);
		}
	}
	for (auto xop : open) {
		const vector<int> &op = xop.y;
		const vector<int> &cl = close[xop.x];
		assert(op.size() == cl.size());
		for (int i = 0; i < (int)op.size(); ++i) {
			pairs.emplace_back(op[i], cl[i]);
		}
	}
	ll answer = 0;
	for (auto &e : pairs) {
		if (e.x > e.y) {
			++answer;
			swap(e.x, e.y);
		}
		// cout << "# " << e.x << " " << e.y << endl;
	}
	for (int i = 0; i < (int)pairs.size(); ++i) {
		for (int j = i + 1; j < (int)pairs.size(); ++j) {
			int a = pairs[i].x, b = pairs[i].y, c = pairs[j].x, d = pairs[j].y;
			if (a > c) {
				swap(a, c), swap(b, d);
			}
			assert(a < c);
			assert(a < b && c < d);
			if (a < b && b < c && c < d) {
				answer += 0;
			} else if (a < c && c < b && b < d) {
				answer += 1;
			} else if (a < c && c < d && d < b) {
				answer += 2;
			} else {
				assert(false);
			}
		}
	}
	return answer;
}

#ifdef LC
#include "grader.cpp"
#endif

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