Submission #1107164

#	Time	Username	Problem	Language	Result	Execution time	Memory
1107164		xnqs	Triple Jump (JOI19_jumps)	C++17	5 / 100	4046 ms	38436 KiB

jumps

// TODO implement optimally

#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#include <utility>
#include <algorithm>
#include <cmath>

int x, q;
int arr[500005];
int sp_tb[19][500005];

void build_sparse_table() {
	for (int l = 1; l < 19; l++) {
		for (int i = 1; i+(1<<l)-1 <= x; i++) {
			sp_tb[l][i] = std::max(sp_tb[l-1][i],sp_tb[l-1][i+(1<<(l-1))]);
		}
	}
}

int max_query(int l, int r) {
	int lvl = 31-__builtin_clz(r-l+1);
	return std::max(sp_tb[lvl][l], sp_tb[lvl][r-(1<<lvl)+1]);
}

struct PQComp {
	bool operator() (int a, int b) {
		return arr[a] < arr[b];
	}
};

// take the 2 maxes, let their positions be 1 and 2
// therefore we have the following cases
//
// 1: ---1##--2
// 2: --###1--2
// 3: -1-2-####
int query(int l, int r) {
	std::priority_queue<int, std::vector<int>, PQComp> pq;
	for (int i = l; i <= r; i++) {
		pq.emplace(i);
	}

	std::vector<int> pos;
	while (!pq.empty()&&pos.size()<50000) {
		int k = pq.top();
		pq.pop();
		pos.emplace_back(k);
	}

	int ret = 0;
	for (int i = 0; i < pos.size(); i++) {
		int m1 = pos[i];
		for (int j = i+1; j < pos.size() && j-i <= 500; j++) {
			int m2 = pos[j];
			if (m1>m2) std::swap(m1,m2);

			int le, ri;
			
			//std::cout << m1 << " " << m2 << "\n";

			// 1
			if (m1+1<m2) {
				le = m1+1;
				ri = (m1+m2)/2;
				//std::cout << "1 " << le << " " << ri << "\n";
				ret = std::max(ret,arr[m1]+arr[m2]+max_query(le,ri));
			}

			// 2
			if (m1-1>=l) {
				le = std::max(l,m1-(m2-m1));
				ri = m1-1;
				ret = std::max(ret,arr[m1]+arr[m2]+max_query(le,ri));
				//std::cout << "2 " << le << " " << ri << "\n";
			}
			
			// 3
			if (m2+(m2-m1)<=r) {
				le = m2+(m2-m1);
				ri = r;
				ret = std::max(ret,arr[m1]+arr[m2]+max_query(le,ri));
				//std::cout << "3 " << le << " " << ri << "\n";
			}

			//std::cout << "\n";
		}
	}

	return ret;
}

int main() {
	std::ios_base::sync_with_stdio(false);
	std::cin.tie(NULL);
	std::cout.tie(NULL);

	std::cin >> x;
	for (int i = 1; i <= x; i++) {
		std::cin >> arr[i];
		sp_tb[0][i] = arr[i];
	}

	build_sparse_table();
	std::cin >> q;
	while (q--) {
		int l, r;
		std::cin >> l >> r;
		std::cout << query(l,r) << "\n";
	}
}

Compilation message (stderr)

jumps.cpp: In function 'int query(int, int)':
jumps.cpp:54:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   54 |  for (int i = 0; i < pos.size(); i++) {
      |                  ~~^~~~~~~~~~~~
jumps.cpp:56:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   56 |   for (int j = i+1; j < pos.size() && j-i <= 500; j++) {
      |                     ~~^~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 0 / 14
• Subtask 3: 0 / 27
• Subtask 4: 0 / 54