Submission #61151

#	Time	Username	Problem	Language	Result	Execution time	Memory
61151		Eae02	Boat (APIO16_boat)	C++14	9 / 100	194 ms	174544 KiB

boat

#include <bits/stdc++.h>
	
uint64_t PRIME = 1000000007;
	
std::vector<std::pair<uint64_t, uint64_t>> schools;
	
std::unordered_map<uint64_t, uint64_t> memo[500];
	
uint64_t count(int i, uint64_t min)
{
	if (i >= schools.size())
		return 1;
	auto mIt = memo[i].find(min);
	if (mIt != memo[i].end())
		return mIt->second;
	
	uint64_t c = count(i + 1, min);
	for (uint64_t n = std::max(schools[i].first, min == 0 ? 0 : (min + 1)); n <= schools[i].second; n++)
	{
		c = (c + count(i + 1, n)) % PRIME;
	}
	
	memo[i].insert(std::make_pair(min, c));
	return c;
}

int64_t negMod(int64_t x)
{
	int64_t r = x % PRIME;
	return r < 0 ? (r + PRIME) : r;
}

int main()
{
	int N;
	std::cin >> N;
	
	bool allSame = true;
	uint64_t max2 = 0;
	
	schools.resize(N);
	for (int i = 0; i < N; i++)
	{
		std::cin >> schools[i].first;
		std::cin >> schools[i].second;
		if (schools[i].first != schools[i].second)
			allSame = false;
		max2 = std::max(max2, schools[i].second);
	}
	
	if (allSame)
	{
		std::cout << (count(0, 0) - 1) << std::endl;
	}
	else
	{
		std::vector<int64_t> waysElim(max2 + 1);
		int64_t ways = 1;
		for (int i = 0; i < N; i++)
		{
			const int64_t prevWays = ways;
			
			const int64_t d = schools[i].second - schools[i].first + 1;
			ways = (ways * ((d + 1) % PRIME)) % PRIME;
			
			for (int64_t j = 0; j < d; j++)
			{
				int64_t eI = schools[i].second - j;
				ways = negMod(ways - waysElim[eI]);
				waysElim[eI] = negMod(((j + 1) % PRIME) * prevWays - waysElim[eI]);
			}
		}
		std::cout << negMod(ways - 1) << std::endl;
	}
}

Compilation message (stderr)

boat.cpp: In function 'uint64_t count(int, uint64_t)':
boat.cpp:11:8: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  if (i >= schools.size())
      ~~^~~~~~~~~~~~~~~~~

• Subtask 1: 9 / 9
• Subtask 2: 0 / 22
• Subtask 3: 0 / 27
• Subtask 4: 0 / 42