Submission #1304385

#	Time	Username	Problem	Language	Result	Execution time	Memory
1304385		the_commando_x	Gondola (IOI14_gondola)	C++17	100 / 100	24 ms	6100 KiB

gondola

#include "gondola.h"

#include <bits/stdc++.h>
using namespace std;

int valid(int n, int inputSeq[])
{
	unordered_set<int> seen;
	for (int i = 0; i < n; ++i)
		if (seen.count(inputSeq[i]))
			return 0;
		else
			seen.insert(inputSeq[i]);

	int start = -1;
	for (int i = 0; i < n; ++i)
		if (inputSeq[i] <= n)
		{
			start = i;
			break;
		}

	if (start != -1)
	{
		int base = inputSeq[start];
		for (int i = 0; i < n; ++i)
		{
			int expected = (base + i - start) % n;
			if (expected <= 0)
				expected += n;

			if (inputSeq[i] <= n && inputSeq[i] != expected)
				return 0;
		}
	}
	return 1;
}

int replacement(int n, int gondolaSeq[], int replacementSeq[])
{
	int start = 0;
	for (int i = 0; i < n; ++i)
		if (gondolaSeq[i] <= n)
		{
			start = i;
			break;
		}

	int base = gondolaSeq[start];

	vector<pair<int, int>> chains; // {final replacement number, current replacement number}

	for (int i = 0; i < n; ++i)
	{
		int expected = (base + i - start) % n;
		if (expected <= 0)
			expected += n;

		if (gondolaSeq[i] > n)
			chains.push_back({gondolaSeq[i], expected});
	}

	sort(chains.begin(), chains.end(), greater<pair<int, int>>());

	int idx = 0, nextReplacement = n + 1;

	while (chains.size() > 1)
	{
		if (chains.back().first > nextReplacement)
		{
			replacementSeq[idx++] = chains[0].second;
			chains[0].second = nextReplacement;
		}
		else
		{
			replacementSeq[idx++] = chains.back().second;
			chains.pop_back();
		}
		++nextReplacement;
	}

	if (chains.size())
		while (nextReplacement <= chains[0].first)
		{
			replacementSeq[idx++] = chains[0].second;
			chains[0].second = nextReplacement++;
		}

	return idx;
}

const long long MOD = 1e9 + 9;

long long mod_pow(long long a, long long b, long long m = MOD)
{
	a %= m;
	long long res = 1;
	while (b > 0)
	{
		if (b & 1)
			res = res * a % m;
		a = a * a % m;
		b >>= 1;
	}
	return res;
}

int countReplacement(int n, int inputSeq[])
{
	if (!valid(n, inputSeq))
		return 0;

	vector<long long> replacements;

	for (int i = 0; i < n; ++i)
		if (inputSeq[i] > n)
			replacements.push_back(inputSeq[i]);

	sort(replacements.begin(), replacements.end());

	if (replacements.size() < 2)
		return 1;

	long long ans = 1, prevReplacement = n;
	for (int i = 0; i < replacements.size(); ++i)
	{
		long long repeatedBroken = (replacements[i] - prevReplacement) - 1,
				  availableSeg = replacements.size() - i;

		ans = (ans * mod_pow(availableSeg, repeatedBroken)) % MOD;

		prevReplacement = replacements[i];
	}

	if (replacements.size() == n)
		return (ans * n) % MOD;

	return ans;
}

• Subtask 1: 5 / 5
• Subtask 2: 5 / 5
• Subtask 3: 10 / 10
• Subtask 4: 5 / 5
• Subtask 5: 10 / 10
• Subtask 6: 20 / 20
• Subtask 7: 5 / 5
• Subtask 8: 15 / 15
• Subtask 9: 15 / 15
• Subtask 10: 10 / 10