Submission #550090

#	Time	Username	Problem	Language	Result	Execution time	Memory
550090		PunnyBunny	Data Transfer (IOI19_transfer)	C++17	100 / 100	44 ms	2560 KiB

transfer

#include "transfer.h"

#include <bits/stdc++.h>
using namespace std;
std::vector<int> get_attachment(std::vector<int> source) {
    int n = source.size(), sum = 0;
    for (int i = 0; i < n; ++i) {
        sum ^= (i + 1) * source[i];
    }

    int k = n == 63 ? 7 : 9;
    vector<int> res(k);
    for (int i = 0; i < 1 << k; ++i) {
        int x = 0;
        for (int j = 0; j < k - 1; ++j) x ^= (i >> j & 1) * (n + 1 + (1 << j));
        x ^= (i >> (k - 1) & 1) * (n + 1);
        if (x == sum) {
            for (int j = 0; j < k; ++j) res[j] = i >> j & 1;
            break;
        }
    }
    return res;
}

std::vector<int> retrieve(std::vector<int> data) {
    int n = data.size() > 100 ? 255 : 63, sum = 0;
    for (int i = 0; i < n; ++i) {
        sum ^= (i + 1) * data[i];
    }

    for (int i = n; i < data.size(); ++i) {
        if (i == data.size() - 1) {
            sum ^= data[i] * (n + 1);
        } else {
            sum ^= data[i] * (n + 1 + (1 << (i - n)));
        }
    }

    if (sum > 0) data[sum - 1] ^= 1;
    return {data.begin(), data.begin() + n};
}

Compilation message (stderr)

transfer.cpp: In function 'std::vector<int> retrieve(std::vector<int>)':
transfer.cpp:31:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   31 |     for (int i = n; i < data.size(); ++i) {
      |                     ~~^~~~~~~~~~~~~
transfer.cpp:32:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   32 |         if (i == data.size() - 1) {
      |             ~~^~~~~~~~~~~~~~~~~~

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