Submission #990636

#	Time	Username	Problem	Language	Result	Execution time	Memory
990636		aaaaaarroz	Data Transfer (IOI19_transfer)	C++17	100 / 100	46 ms	2592 KiB

transfer

#include "transfer.h"


std::vector<int> get_attachment(std::vector<int> source) {

	std::vector<int> v;

	int x = 0;

	for (int i = 0; i < source.size(); i++)

		if (source[i]) x ^= (i + 1);


	int last = 0;

	if (source.size() < 64) {

		for (int i = 0; i < 6; i++) {

			v.push_back(x & 1);

			if (x & 1) last = 1 - last;

			x >>= 1;

		}

	} else {

		for (int i = 0; i < 8; i++) {

			v.push_back(x & 1);

			if (x & 1) last = 1 - last;

			x >>= 1;

		}

	}

	v.push_back(last);

	return v;

}


std::vector<int> retrieve(std::vector<int> data) {

	int last = data.back();

	data.pop_back();

	int actual_last = 0, x = 0;

	if (data.size() < 71) {

		for (int i = 0; i < 6; i++) {

			x <<= 1;

			x += data.back();

			if (data.back()) actual_last = 1 - actual_last;

			data.pop_back();

		}

	} else {

		for (int i = 0; i < 8; i++) {

			x <<= 1;

			x += data.back();

			if (data.back()) actual_last = 1 - actual_last;

			data.pop_back();

		}

	}


	if (actual_last != last) return std::vector<int>(data.begin(), data.end());


	int actual_x = 0;

	for (int i = 0; i < data.size(); i++) {

		if (data[i]) actual_x ^= (i + 1);

	}


	int error = actual_x ^ x;

	if (error == 0) return data;


	data[error - 1] = 1 - data[error - 1];

	return data;

}

Compilation message (stderr)

transfer.cpp: In function 'std::vector<int> get_attachment(std::vector<int>)':
transfer.cpp:10:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   10 |  for (int i = 0; i < source.size(); i++)
      |                  ~~^~~~~~~~~~~~~~~
transfer.cpp: In function 'std::vector<int> retrieve(std::vector<int>)':
transfer.cpp:94:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   94 |  for (int i = 0; i < data.size(); i++) {
      |                  ~~^~~~~~~~~~~~~

• Subtask 1: 60 / 60
• Subtask 2: 40 / 40