Ones

Time limit: 1s Memory limit: 256MB Input: Output:

Problem Statement

Radko again wants to know Marti’s sequence p1,p2,,pnp_1, p_2, \ldots, p_n. This time, Marti decided to be more helpful and directly say that the sequence consists of nn bits of 00 and 11, exactly kk of which are 11. This time he will only answer the following question: “Is there a 11 among pl,pl+1,,prp_l, p_{l+1}, \ldots, p_r?”

Unfortunately, Radko is still too busy and again outsources the task to you. Your program will be tested on 𝑛𝑡𝑒𝑠𝑡𝑠 subtests for each test, and your score will be calculated based on the total number of questions you use to find the respective sequences.

Implementation details

Your function guessOnes has the following prototype:

std::vector<int> guessOnes(int n, int k);

It will be called ntestsn_{tests} times for each test and will receive as arguments the sequence length nn and the number of ones kk. The function should return a vector of kk numbers - the positions of the ones in ascending order.
The jury’s function hasOnes has the following prototype:

bool hasOnes(int l, int r);

Your program can call it as many times as it wants. It receives two indexes ll and rr from 11 to nn for which you want to ask a question. The function returns whether there is a 11 among pl,pl+1,,prp_l, p_{l+1}, \ldots, p_r. It works with complexity O(1) O(1)~.
Your program must implement the function guessOnesguessOnes, but should not contain a function main. Also, it must not read from the standard input or print to the standard output. Your program must also include the header file ones.hones.h by an instruction to the preprocessor: #include "ones.h"
As long as it respects these conditions, your program can contain any helper functions, variables, constants, and so on.

Constraints

  • Every sequence is uniform random generated.
  • n=100 000n = 100\ 000
  • ntests=100n_{tests} = 100

Subtasks and scoring

The fraction of points you will get on a subtask depends on the total number of questions you ask on a subtest, qparticipantq_{participant}, and the subtask constant qauthorq_{author}.
If qparticipantqauthorq_{participant} \leq q_{author}. score=1score = 1
Otherwise score=11qauthorqparticipant4score = 1 - \sqrt[4]{1 - \frac{q_{author}}{q_{participant}}}

Subtasks

# Points K qauthorq_{author}
1 10 1010 1448014480
2 10 2020 2720127201
3 10 5050 6190861908
4 10 100100 114144114144
5 10 200200 208697208697
6 10 500500 455937455937
7 10 1 0001\ 000 811792811792
8 10 2 0002\ 000 14223961422396
9 10 5 0005\ 000 28796752879675
10 10 10 00010\ 000 47237794723779

Local testing

The file Lgrader.cpp is provided on the system, with which you can test your program locally. To do so, you need to add #include "Lgrader.cpp" to your code.
The first line of the standard input contains the numbers n,kn, k and ntestsn_{tests}.
The next ntestsn_{tests} lines contain kk numbers each – the positions of the ones. If your program successfully finds the correct sequence for each test, it will output the total number of questions you used for all sequences.

Log in or sign up to be able to send submissions!