Submission #143473

#	Time	Username	Problem	Language	Result	Execution time	Memory
143473		dolphingarlic	Data Transfer (IOI19_transfer)	C++14	100 / 100	138 ms	2664 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:6:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < source.size(); i++)
                     ~~^~~~~~~~~~~~~~~
transfer.cpp: In function 'std::vector<int> retrieve(std::vector<int>)':
transfer.cpp:50:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < data.size(); i++) {
                     ~~^~~~~~~~~~~~~

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