Submission #1210318

#	Time	Username	Problem	Language	Result	Execution time	Memory
1210318		madamadam3	Arranging Shoes (IOI19_shoes)	C++20	10 / 100	1129 ms	1078712 KiB

shoes

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

using namespace std;

typedef long long ll;

int n;

struct State {
	vector<pair<int, int>> swaps;
	int moves;
};

bool check_valid(State &state, vector<int> &initial) {
	vector<int> arrangement = initial;
	for (auto &el : state.swaps) {
		swap(arrangement[el.first], arrangement[el.second]);
	}

	bool valid = true;
	for (int i = 0; i < n; i++) {
		valid = valid && (abs(arrangement[2*i]) == abs(arrangement[2*i+1])) && (arrangement[2*i] < 0 && arrangement[2*i+1] > 0);
	}
	return valid;
}


// left shoe if s[i] < 0
// right shoe if s[i] > 0
ll count_swaps(vector<int> s) {
	n = s.size() / 2;
	int minimum = 0;

	queue<State> q;
	State best;

	q.push(State{{}, 0});

	while (!q.empty()) {
		State cur = q.front();
		q.pop();

		if (check_valid(cur, s)) {
			minimum = cur.moves;
			best = cur;
			break;
		}

		for (int i = 1; i < 2*n; i++) {
			for (int j = i-1; j < i+2 && j < 2*n; j++) {
				if (i == j) continue;
				vector<pair<int, int>> swaps = cur.swaps;
				swaps.push_back({i, j});
				q.push(State{swaps, cur.moves + 1});
			}
		}
	}
	
	// cout << "Fastest fix is " << best.moves << " moves\n";
	// for (auto &el : best.swaps) {
	// 	cout << "Swapped " << el.first << " and " << el.second << "\n";
	// }
	return minimum;
}

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