Submission #1195217

#	Time	Username	Problem	Language	Result	Execution time	Memory
1195217		madamadam3	Sorting (IOI15_sorting)	C++20	8 / 100	331 ms	589824 KiB

sorting

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

using namespace std;

#define all(x) (x).begin(), (x).end()
#define FOR(i, a, b) for (int i = a; i < b; i++)
#define each(a, x) for (auto &x : a) 
#define srt(x) sort(all(x))
#define sz(x) (int) (x).size()
#define pb push_back
#define trace(x) for (auto &el : x) cout << el << " "

using pi = pair<int, int>;
using vi = vector<int>;
using vpi = vector<pi>;

struct State {
	vi cur; int turn;
	vpi steps;
};

bool is_sorted(vi inp) {
	int n = sz(inp);
	vi to_srt = vi(all(inp));
	srt(to_srt);

	FOR(i, 0, n) {
		if (inp[i] != to_srt[i]) return false;
	}
	return true;
}

/*
	N = length of seq
	S = initial seq
	M = swaps by ermek
	X[i], Y[i] = ith swap of ermek
	P[i], Q[i] = swaps player makes
	function returns R (number of swaps)
*/

int findSwapPairs(int N, int S[], int M, int X[], int Y[], int P[], int Q[]) {
	int n = N;
	int R = 1;

	vi initial; FOR(i, 0, n) initial.pb(S[i]);
	vpi swaps;
	
	// int curturn = 0;
	// FOR(i, 0, n) {
	// 	int qidx = 0;
	// 	while (initial[qidx] != i) qidx++;
	// 	if (qidx == i || qidx <= 1 || i <= 1) continue;
		
	// 	swap(initial[X[curturn]], initial[Y[curturn]]);
	// 	curturn++;
	// 	swap(initial[qidx], initial[i]);
	// 	swaps.pb({i, qidx});
	// }

	queue<State> q;
	q.push(State{initial, 0, {}});

	State best;
	while (!q.empty()) {
		auto cur = q.front();
		q.pop();
		if (is_sorted(cur.cur)) {
			best = cur;
			break;
		}

		vi narr = vi(all(cur.cur));
		swap(narr[X[cur.turn]], narr[Y[cur.turn]]);
		
		FOR(i, 0, n) {
			if (cur.cur[i] == i) continue;
			FOR(j, i + 1, n) {
				if (cur.cur[j] == j) continue;
				vi nnarr = vi(all(narr));
				swap(nnarr[i], nnarr[j]);
				vpi nsteps = vpi(all(cur.steps));
				nsteps.pb({i, j});

				q.push(State {nnarr, cur.turn + 1, nsteps});
			}
		}
	}

	R = sz(best.steps);
	FOR(i, 0, R) {
		P[i] = best.steps[i].first;
		Q[i] = best.steps[i].second;
	}
	// trace(best.cur); cout << "\n";

	// R = sz(swaps);
	// FOR(i, 0, R) {
	// 	P[i] = swaps[i].first;
	// 	Q[i] = swaps[i].second;
	// }
	return R;
}

• Subtask 1: 8 / 8
• Subtask 2: 0 / 12
• Subtask 3: 0 / 16
• Subtask 4: 0 / 18
• Subtask 5: 0 / 20
• Subtask 6: 0 / 26