Submission #1194571

#	Time	Username	Problem	Language	Result	Execution time	Memory
1194571		Nelt	Message (IOI24_message)	C++20	72.85 / 100	401 ms	864 KiB

message

#include "message.h"
#include <bits/stdc++.h>
#define endl "\n"
#define ll long long
using namespace std;
ll p[2][31];
void precomp()
{
    for (ll i = 0; i < 31; i++) p[0][i] = i;
    for (ll i = 0; i < 31; i++) p[1][30 - i] = p[0][i];
}
ll cost(vector<bool> &c, bool rev)
{
    ll tot = 0;
    ll ptr = 0, sz = 0;
    while (sz < 16)
    {
        tot++;
        for (ll i = 0; i < sz and ptr < 31 and sz < 16; i++, ptr++)
            sz += c[p[rev][ptr]] == 0;
        if ((16 - sz) * 2 > 31 - ptr)
        {
            if (c[p[rev][ptr]] == 0)
                sz++;
            ptr++;
        }
    }
    return tot;
}
void send_message(vector<bool> a, vector<bool> c)
{
    precomp();
    vector<bool> msg(31, 0);
    bool flg = cost(c, 1) < cost(c, 0);
    send_packet(vector<bool>(31, flg));
    vector<ll> fixed;
    ll ptr = 0;
    bool ok = false;
    while (fixed.size() < 16)
    {
        ll i;
        for (i = 0; i < fixed.size() and ptr < 31; i++, ptr++)
        {
            msg[fixed[i]] = c[p[flg][ptr]];
            if (c[p[flg][ptr]] == 0)
                fixed.push_back(p[flg][ptr]);
        }
        if (i + 3 < fixed.size())
        {
            for (ll j = 0; j < 4; j++)
                msg[fixed[i + j]] = a.size() >> j & 1;
            ok = true;
        }
        if ((16 - fixed.size()) * 2 > 31 - ptr)
        {
            for (ll i = ptr; i < 31; i++) 
                msg[p[flg][i]] = c[p[flg][ptr]];
            if (c[p[flg][ptr]] == 0)
                fixed.push_back(p[flg][ptr]);
            ptr++;
        }
        send_packet(msg);
    }
    if (fixed.size() != 16)
        exit(0);
    for (ll i = 0; i < 16; i++)
        msg[fixed[i]] = (a.size() >> i & 1);
    if (!ok)
        send_packet(msg);
    for (ll i = 0; i < a.size(); i += 16)
    {
        for (ll j = 0; j + i < a.size() and j < 16; j++)
            msg[fixed[j]] = a[i + j];
        send_packet(msg);
    }
}
bool majority(vector<bool> &c, ll ind, bool flg)
{
    ll cnt1 = 0;
    for (ll i = ind; i < 31; i++) cnt1 += c[p[flg][i]];
    return cnt1 * 2 > 31 - ind;
}
vector<bool> receive_message(vector<vector<bool>> a)
{
    precomp();
    vector<bool> c(31, 1);
    bool flg = majority(a[0], 0, 0);
    ll ptr = 0, cur = 1;
    vector<ll> fixed;
    bool ok = false;
    ll rem = 0;
    while (fixed.size() < 16)
    {
        ll i;
        for (i = 0; i < fixed.size() and ptr < 31; i++, ptr++)
        {
            c[p[flg][ptr]] = a[cur][fixed[i]];
            if (c[p[flg][ptr]] == 0)
                fixed.push_back(p[flg][ptr]);
        }
        if (i + 3 < fixed.size())
        {
            for (ll j = 0; j < 4; j++)
                rem += a[cur][fixed[i + j]] ? (1 << j) : 0;
            ok = true;
        }
        if ((16 - fixed.size()) * 2 > 31 - ptr)
        {
            c[p[flg][ptr]] = majority(a[cur], ptr, flg);
            if (c[p[flg][ptr]] == 0)
                fixed.push_back(p[flg][ptr]);
            ptr++;
        }
        cur++;
    }
    if (fixed.size() != 16)
        exit(0);
    ll sz = 0;
    if (!ok)
    {
        for (ll i = 0; i < 16; i++)
            if (a[cur][fixed[i]])
                sz += 1 << i;
        cur++;
    }
    else
        sz = (a.size() - cur - (rem > 0)) << 4 | rem;
    vector<bool> ans(sz);
    for (ll i = 0; i < sz; i++)
        ans[i] = a[cur + (i >> 4)][fixed[i & 15]];
    return ans;
}

• Subtask 0: 0 / 0
• Subtask 1: 10 / 10
• Subtask 2: 62.8504 / 90