Submission #1206096

#	Time	Username	Problem	Language	Result	Execution time	Memory
1206096		lighton	Flight to the Ford (BOI22_communication)	C++20	77 / 100	1146 ms	3260 KiB

communication

#include"communication.h"
#include<bits/stdc++.h>
#define pb push_back
#define all(v) v.begin(),v.end()
#define forf(i,s,e) for(int i = s; i<=e; i++)
#define forb(i,s,e) for(int i = s; i>=e; i--)
#define idx(i,v) (int)(lower_bound(all(v),i)-v.begin())
#define comp(v) v.erase(unique(all(v)),v.end())
#define sz(v) (int)v.size()
#define fs first
#define se second
#define SP << " " <<
#define LN << "\n"
#define IO cin.tie(0);cout.tie(0);ios_base::sync_with_stdio(false);
using namespace std;
typedef long long ll;
ll inf = 1e18;

vector<int> message[4] =
        {{0,0,0,0},
         {0,1,1,0},
         {1,0,0,1},
         {1,1,1,1}};
vector<int> contrast(vector<int> R){
    vector<int> ret;
    forf(x,0,3){
        int f = 1;
        forf(i,0,2) if(R[i]!=message[x][i] && R[i+1]!=message[x][i+1]) f = 0;
        if(f) ret.pb(x);
    }
    return ret;
}

int fib[31];
void getfib(){
    if(fib[1]) return;
    fib[0] = 1, fib[1] = 2;
    forf(i,2,30) fib[i] = fib[i-1]+fib[i-2];
}

int fibidx(int n, int x){
    int ret = 0;
    forf(i,0,n-1) if(x &(1<<i)) ret += fib[i];
    return ret;
}

int kthfib(int n, int k){
    int ret = 0;
    forb(i,n-1,0) if(k-fib[i] >= 0) k -= fib[i], ret+=(1<<i);
    return ret;
}

int piv = 100;
vector<int> enc(int N, int X){
    if(N==2) return {0,1};
    if(N==1) return {0};

    if(N>=piv) {
        int n = 1;
        while ((1 << n) < N) n++;
        getfib();

        int R = 0;
        forf(i, 0, n - 1) R += send((X & (1 << i)) ? 1 : 0) * (1 << i);
        int nx = fibidx(n,X ^ R);

        auto v = enc(fib[n], nx);
        vector<int> ret;
        for (int i : v) if(i < fib[n] && (R ^ kthfib(n,i)) < N) ret.pb(R ^ kthfib(n,i));
        return ret;
    }
    else{
        int p[5];
        forf(i,0,4) p[i] = (double)N / 4 * i;
        int I;
        forf(i,0,4) if(X>=p[i]) I = i;

        vector<int> R;
        forf(i,0,3) R.pb(send(message[I][i]));
        vector<pair<int,int> > intv;
        int nN=0,nX=0;
        for(auto i : contrast(R)) intv.pb({p[i],p[i+1]}), nN += p[i+1]-p[i];
        if(X < intv[0].se) nX = X-intv[0].fs;
        else nX = intv[0].se-intv[0].fs + X-intv[1].fs;

        vector<int> res = enc(nN,nX);
        vector<int> ret;
        for(auto i : res){
            if(i < intv[0].se-intv[0].fs) ret.pb(intv[0].fs+i);
            else ret.pb(intv[1].fs+ i-(intv[0].se-intv[0].fs));
        }
        return ret;
    }
}

vector<int> dec(int N){
    if(N==2) return {0,1};
    if(N==1) return {0};

    if(N>=piv) {
        int n = 1;
        while ((1 << n) < N) n++;
        getfib();

        int R = 0;
        forf(i, 0, n - 1) R += receive() * (1 << i);
        auto v = dec(fib[n]);
        vector<int> ret;
        for (int i : v) if(i < fib[n] && (R ^ kthfib(n,i)) < N) ret.pb(R ^ kthfib(n,i));
        return ret;
    }
    else{
        int p[5];
        forf(i,0,4) p[i] = (double)N / 4 * i;

        vector<int> R;
        forf(i,0,3) R.pb(receive());
        vector<pair<int,int> > intv;
        int nN=0;
        for(auto i : contrast(R)) intv.pb({p[i],p[i+1]}), nN += p[i+1]-p[i];

        vector<int> res = dec(nN);
        vector<int> ret;
        for(auto i : res){
            if(i < intv[0].se-intv[0].fs) ret.pb(intv[0].fs+i);
            else ret.pb(intv[1].fs+ i-(intv[0].se-intv[0].fs));
        }
        return ret;
    }
}

void encode(int N, int X) {
    auto trash = enc(N,X-1);
}

std::pair<int, int> decode(int N) {
    vector<int> ans = dec(N);
    sort(all(ans));
    if(sz(ans)== 1) return {ans[0]+1,ans[0]+1};
    else return {ans[0]+1, ans[1]+1};
}

• Subtask 1: 15 / 15
• Subtask 2: 62 / 85