Submission #627293

#	Time	Username	Problem	Language	Result	Execution time	Memory
627293		JustInCase	Catfish Farm (IOI22_fish)	C++17	44 / 100	134 ms	10852 KiB

fish

#include <iostream>
#include <string>
#include <vector>
#include <queue>
#include <stack>
#include <array>
#include <algorithm>
#include <numeric>
#include <map>
#include <unordered_map>
#include <set>
#include <cstring>
#include <cmath>
#include <iomanip>
#include <cassert>
#include <random>
#include <cstdlib>

#define debug(x) std::cout << #x << " " << (x) << '\n';
#define pb push_back
#define mp std::make_pair
#define remax(a, b) a = std::max((a), (b));
#define remin(a, b) a = std::min((a), (b));

#define maxWeights max_weights

int64_t solveSmallN(int32_t n, int32_t m, std::vector<int32_t> x, std::vector<int32_t> y,
			std::vector<int32_t> w) {
	const int32_t MAX_N = 300;

	std::array<std::array<int64_t, MAX_N>, MAX_N> wPrefSums {};
	std::array<std::array<std::array<int64_t, 3>, MAX_N + 1>, MAX_N + 1> dp {};

	auto getWRangeSum = [&wPrefSums](int32_t startRow, int32_t endRow, int32_t column) -> int64_t {
		if(endRow <= startRow) {
			return 0;
		}

		return wPrefSums[endRow - 1][column] - (startRow == 0 ? 0 : wPrefSums[startRow - 1][column]);
	};

	for(int32_t i = 0; i < m; i++) {
		wPrefSums[y[i]][x[i]] = (int64_t) w[i];
	}

	for(int32_t j = 0; j < n; j++) {
		for(int32_t i = 1; i < n; i++) {
			wPrefSums[i][j] += wPrefSums[i - 1][j];
		}
	}

	for(int32_t j = 1; j < n; j++) {
		for(int32_t lastK = 0; lastK <= n; lastK++) {
			for(int32_t k = 0; k <= n; k++) {
				if(k == 0) {
					remax(dp[j + 1][lastK][2], dp[j][lastK][0] + getWRangeSum(0, lastK, j));
					remax(dp[j + 1][lastK][2], dp[j][lastK][1] + getWRangeSum(0, lastK, j));
				}

				if(lastK <= k) {
					remax(dp[j + 1][k][0], dp[j][lastK][0] + getWRangeSum(lastK, k, j - 1));
					remax(dp[j + 1][k][0], dp[j][lastK][2] + getWRangeSum(lastK, k, j - 1));
				}
				if(lastK >= k) {
					remax(dp[j + 1][k][1], dp[j][lastK][1] + getWRangeSum(k, lastK, j));
					remax(dp[j + 1][k][1], dp[j][lastK][0] + getWRangeSum(k, lastK, j));
					remax(dp[j + 1][k][0], dp[j][lastK][2]);
				}
			}
		}
	}
	
	int64_t ans = 0;
	for(int32_t k = 0; k <= n; k++) {
		remax(ans, dp[n][k][0]);
		remax(ans, dp[n][k][1]);
		remax(ans, dp[n][k][2]);
	}

	return ans;
}

int64_t solveEvenXs(int32_t n, int32_t m, std::vector<int32_t> x, std::vector<int32_t> y,
			std::vector<int32_t> w) {
	int64_t ans = 0;
	for(int32_t i = 0; i < m; i++) {
		ans += (int64_t) w[i];
	}
	return ans;
}

int64_t solveAllXs0Or1(int32_t n, int32_t m, std::vector<int32_t> x, std::vector<int32_t> y,
			std::vector<int32_t> w) {
	const int32_t MAX_N = 1e5;

	std::array<std::array<int64_t, 2>, MAX_N> wPrefSums {};

	auto getWRangeSum = [&wPrefSums](int32_t startRow, int32_t endRow, int32_t column) -> int64_t {
		if(endRow <= startRow) {
			return 0;
		}

		return wPrefSums[endRow - 1][column] - (startRow == 0 ? 0 : wPrefSums[startRow - 1][column]);
	};

	for(int32_t i = 0; i < m; i++) {
		wPrefSums[y[i]][x[i]] = (int64_t) w[i];
	}

	for(int32_t j = 0; j < 2; j++) {
		for(int32_t i = 1; i < n; i++) {
			wPrefSums[i][j] += wPrefSums[i - 1][j];
		}
	}

	int64_t ans = 0;
	remax(ans, getWRangeSum(0, n, 1));
	remax(ans, getWRangeSum(0, n, 0));

	if(n > 2) {
		for(int32_t i = 0; i <= n; i++) {
			remax(ans, getWRangeSum(0, i, 0) + getWRangeSum(i, n, 1));
		}
	}

	return ans;
}

int64_t solveAllYs0(int32_t n, int32_t m, std::vector<int32_t> x, std::vector<int32_t> w) {
	const int32_t MAX_N = 1e5;

	std::array<int32_t, MAX_N + 1> wByColumn {};
	for(int32_t i = 0; i < m; i++) {
		wByColumn[x[i]] = w[i];
	}
	
	if(n == 2) {
		return std::max(wByColumn[0], wByColumn[1]);
	}

	std::array<std::array<std::array<int64_t, 2>, 2>, MAX_N + 1> dp {};
	dp[2][0][0] = 0;
	dp[2][0][1] = wByColumn[0] + wByColumn[2];
	dp[2][1][0] = wByColumn[1];
	dp[2][1][1] = wByColumn[2];
	for(int32_t j = 3; j <= n; j++) {
		dp[j][0][0] = std::max(dp[j - 1][0][0], dp[j - 1][1][0]);	
		dp[j][0][1] = std::max(dp[j - 1][0][0] + wByColumn[j - 2], dp[j - 1][1][0]) + wByColumn[j];
		dp[j][1][0] = std::max(dp[j - 1][0][1], dp[j - 1][1][1]);
		dp[j][1][1] = std::max(dp[j - 1][0][1], dp[j - 1][1][1]) + wByColumn[j] - wByColumn[j - 1];
	}

	return std::max(dp[n][0][0], dp[n][1][0]);
}

int64_t maxWeights(int32_t n, int32_t m, std::vector<int32_t> x, std::vector<int32_t> y,
                      std::vector<int32_t> w) {
	if(n <= 300) {
		return solveSmallN(n, m, x, y, w);
	}
	else if(std::all_of(x.begin(), x.end(), [](int32_t v) { return !(v & 1); })) {
		return solveEvenXs(n, m, x, y, w);
	}
	else if(std::all_of(x.begin(), x.end(), [](int32_t v) { return (v < 2); })) {
		return solveAllXs0Or1(n, m, x, y, w);
	}
	else if(std::all_of(x.begin(), x.end(), [](int32_t v) { return (v == 0); })) {
		return solveAllYs0(n, m, x, w);
	}

	return 0;
}

• Subtask 1: 3 / 3
• Subtask 2: 6 / 6
• Subtask 3: 0 / 9
• Subtask 4: 14 / 14
• Subtask 5: 21 / 21
• Subtask 6: 0 / 17
• Subtask 7: 0 / 14
• Subtask 8: 0 / 16