Submission #1015308

#	Time	Username	Problem	Language	Result	Execution time	Memory
1015308		aykhn	Carnival Tickets (IOI20_tickets)	C++17	27 / 100	353 ms	108372 KiB

tickets

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

using namespace std;

#define inf 0x3F3F3F3F3F3F3F3F

long long find_maximum(int k, vector<vector<int>> x) {
	int n = x.size();
	int m = x[0].size();
	vector<vector<int>> answer(n, vector<int> (m, -1));
	vector<vector<int>> pre(n, vector<int> (m, 0)), suf(n, vector<int> (m, 0));
	vector<vector<long long>> dp(n, vector<long long> (n / 2 + 5, -inf)), take(n, vector<long long> (k * n / 2 + 5, -1));
	vector<long long> taken(n, 0);
	auto presum = [&](int i, int len)
	{
		if (!len) return 0;
		return pre[i][len - 1];
	};
	auto sufsum = [&](int i, int len)
	{
		if (!len) return 0;
		return suf[i][m - len];
	};
	for (int i = 0; i < n; i++)
	{
		for (int j = 0; j < m; j++) pre[i][j] = (j ? pre[i][j - 1] : 0) + x[i][j];
		for (int j = m - 1; j >= 0; j--) suf[i][j] = (j + 1 < m ? suf[i][j + 1] : 0) + x[i][j];
	}
	for (int i = 0; i <= min(k, k * n / 2); i++) 
	{
		dp[0][i] = sufsum(0, i) - presum(0, k - i);
		take[0][i] = i;
	}
	for (int i = 1; i < n; i++)
	{
		for (int j = 0; j <= k * n / 2; j++)
		{
			for (int l = 0; l <= k; l++)
			{
				if (j - l < 0) continue;
				if (dp[i - 1][j - l] + sufsum(i, l) - presum(i, k - l) > dp[i][j])
				{
					dp[i][j] = dp[i - 1][j - l] + sufsum(i, l) - presum(i, k - l);
					take[i][j] = l;
				}
			}
		}
	}
	int i = n - 1, j = n * k / 2;
	while (i >= 0)
	{
		taken[i] = take[i][j];
		j -= take[i][j];
		i--;
	}
	vector<int> o(n, 0);
	iota(o.begin(), o.end(), 0);
	vector<int> l(n, 0), r(n, 0);
	for (int i = 0; i < n; i++) r[i] = m - taken[i];
	for (int t = 0; t < k; t++)
	{
		sort(o.begin(), o.end(), [&](const int &a, const int &b)
		{
			return r[a] < r[b];
		});
		for (int i = 0; i < o.size() / 2; i++)
		{
			answer[o[i]][r[o[i]]] = t;
			r[o[i]]++;
		}
		for (int i = o.size() / 2; i < o.size(); i++)
		{
			answer[o[i]][l[o[i]]] = t;
			l[o[i]]++;
		}
	}
	allocate_tickets(answer);
	return dp[n - 1][n * k / 2];
}

Compilation message (stderr)

tickets.cpp: In function 'long long int find_maximum(int, std::vector<std::vector<int> >)':
tickets.cpp:67:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   67 |   for (int i = 0; i < o.size() / 2; i++)
      |                   ~~^~~~~~~~~~~~~~
tickets.cpp:72:32: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   72 |   for (int i = o.size() / 2; i < o.size(); i++)
      |                              ~~^~~~~~~~~~

• Subtask 1: 11 / 11
• Subtask 2: 16 / 16
• Subtask 3: 0 / 14
• Subtask 4: 0 / 14
• Subtask 5: 0 / 12
• Subtask 6: 0 / 23
• Subtask 7: 0 / 10