Submission #973176

#	Time	Username	Problem	Language	Result	Execution time	Memory
973176		sleepntsheep	Data Transfer (IOI19_transfer)	C++17	100 / 100	46 ms	2764 KiB

transfer

#include "transfer.h"

std::vector<int> get_attachment(std::vector<int> source) {
    int A;
    if (source.size() == 63) A = 6;
    else A = 8;

    int xorsum = 0;
    std::vector<int> v;
    for (int i = 0; i < (int)source.size(); ++i)
        if (source[i]) xorsum ^= i + 1;
    for (int i = 0; i < A; ++i) v.push_back((xorsum>>i)&1);
    v.push_back(__builtin_parity(xorsum));
    return v;
}

std::vector<int> retrieve(std::vector<int> data) {
    int A;
    if (data.size() < 100) A = 6;
    else A = 8;

    int xorsum = 0;
    int n = (int)data.size() - A - 1;
    for (int i = 0; i < n; ++i)
        if (data[i]) xorsum ^= i + 1;

    int xordat = 0, dat_par = data.back();
    for (int i = n; i < n + A; ++i)
        xordat ^= (data[i]<<(i-n));

    while ((int)data.size() > n) data.pop_back();
    if (__builtin_parity(xordat) != dat_par)
        return data;

    int i = xorsum ^ xordat;
    if(i)
        data[i-1] ^= 1;
    return data;
}

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