Submission #210775

#	Time	Username	Problem	Language	Result	Execution time	Memory
210775		Alexa2001	Data Transfer (IOI19_transfer)	C++17	100 / 100	228 ms	2928 KiB

transfer

#include "transfer.h"
#include <bits/stdc++.h>

using namespace std;

vector<int> get_attachment(vector<int> source) 
{
    vector<int> a;
    
    int n;
    if(source.size() < 64) n = 6;
        else n = 8;

    int xor_bits = 0;
    int i, j;
    for(i=0; i<n; ++i)
    {
        int bit = 0;
        for(j=0; j<source.size(); ++j)
            if(!(j & (1<<i))) bit ^= source[j];
        
        a.push_back(bit);
        xor_bits ^= bit;
    }

    a.push_back(xor_bits);
    return a;
}

vector<int> retrieve(vector<int> data) 
{
    int n;
    if(data.size() < 64 + 7) n = 6;
        else n = 8;

    int xor_bits = 0, m = data.size() - n - 1;
    vector<int> b(n), ans;

    int i, j;
    for(i=0; i<n; ++i)
    {
        int bit = 0;
        for(j=0; j<m; ++j)
            if(!(j & (1<<i))) bit ^= data[j];
        b[i] = bit;
    }

    int bad = 0;
    for(i=0; i<n; ++i)
    {
        if(b[i] != data[m + i]) bad |= (1<<i);
        xor_bits ^= data[m + i];
    }
    ans = data;
    ans.resize(m);

    if(bad && xor_bits == data.back()) 
        ans[bad ^ ((1<<n) - 1)] ^= 1; 

    return ans;
}

Compilation message (stderr)

transfer.cpp: In function 'std::vector<int> get_attachment(std::vector<int>)':
transfer.cpp:19:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(j=0; j<source.size(); ++j)
                  ~^~~~~~~~~~~~~~

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