Submission #1099066

#	Time	Username	Problem	Language	Result	Execution time	Memory
1099066		origabai	Flight to the Ford (BOI22_communication)	C++17	15 / 100	353 ms	2940 KiB

communication

#include<bits/stdc++.h>
using namespace std;
#include"communication.h"
//
// --- Sample implementation for the task communication ---
//
// To compile this program with the sample grader, place:
//     communication.h communication_sample.cpp sample_grader.cpp
// in a single folder, then open the terminal in this directory (right-click onto an empty spot in the directory,
// left click on "Open in terminal") and enter e.g.:
//     g++ -std=c++17 communication_sample.cpp sample_grader.cpp
// in this folder. This will create a file a.out in the current directory which you can execute from the terminal
// as ./a.out
// See task statement or sample_grader.cpp for the input specification
//
typedef pair<int,int> pi;

pair<int,int> sendtrit(int X){
    int a,b,c;
    if (X==0){
        a=send(0);b=send(0);c=send(0);
    } else if (X==1){
        a=send(1);b=send(1);c=send(1);
    } else if (X==2){
        a = send(0);
        if (a==1){
            b=send(1);c=send(1);
        } else {
            b=send(0);c=send(1);
        }
    }
    pi ans[8] = {{0,2},{0,2},{0,1},{1,2},{0,0},{0,1},{1,2},{1,2}};
    return ans[(a<<2)+(b<<1)+c];
}

pair<int,int> recvtrit(){
    pi ans[8] = {{0,2},{0,2},{0,1},{1,2},{0,0},{0,1},{1,2},{1,2}};
    return ans[(receive() << 2) + (receive() << 1) + (receive())];
}

void encode(int N, int X) {
    int sz = ceil(log(N+1)/log(3));
    int act[sz];
    pi tr[sz];
    int j = X;
    for (int i=0;i<sz;i++){
        act[i] = j%3;
        tr[i] = sendtrit(j%3);
        j/=3;
    }
    int A=tr[0].first,B=tr[0].second;
    bool A_actual = A==act[0];
    int pow = 1;
    for (int i=1;i<sz;i++){
        pow*=3;
        int c = tr[i].first,d = tr[i].second;
        int opt1[] = {c*pow+A,d*pow+A,c*pow+B,d*pow+B};
        int actual = opt1[A_actual ? d==act[i] : 2 + (d==act[i])];
        pi curr;
        if (actual == opt1[0] || actual == opt1[1]){
            curr = sendtrit(0);
        } else if (actual == opt1[2]){
            curr = sendtrit(1);
        } else if (actual == opt1[3]){
            curr = sendtrit(2);
        }
        vector<int> opt2;
        if (curr.first == 0){
            opt2.push_back(opt1[0]);
            opt2.push_back(opt1[1]);
        } else {
            opt2.push_back(opt1[1+curr.first]);
        }
        opt2.push_back(opt1[1+curr.second]);
        if (opt2.size() == 2){
            A = opt2[0];
            B = opt2[1];
            A_actual = (A==actual);
        } else {
            if (actual==opt2[0]){
                curr = sendtrit(0);
            } else if (actual==opt2[1]){
                curr = sendtrit(1);
            } else {
                curr = sendtrit(2);
            }
            A = opt2[curr.first];
            B = opt2[curr.second];
            A_actual = (A==actual);
        }
    }
}

std::pair<int, int> decode(int N) {
    int sz = ceil(log(N+1)/log(3));
    pi tr[sz];
    for (int i=0;i<sz;i++){
        tr[i] = recvtrit();
    }
    int A=tr[0].first,B=tr[0].second;
    int pow = 1;
    for (int i=1;i<sz;i++){
        pow *= 3;
        int c = tr[i].first,d = tr[i].second;
        int opt1[] = {c*pow+A,d*pow+A,c*pow+B,d*pow+B};
        pi curr = recvtrit();
        vector<int> opt2;
        if (curr.first == 0){
            opt2.push_back(opt1[0]);
            opt2.push_back(opt1[1]);
        } else {
            opt2.push_back(opt1[1+curr.first]);
        }
        opt2.push_back(opt1[1+curr.second]);
        if (opt2.size()==2){
            A = opt2[0];
            B = opt2[0];
        } else {
            curr = recvtrit();
            A = opt2[curr.first];
            B = opt2[curr.second];
        }
    }
    A = max(1,A);
    A = min(N,A);
    B = max(1,B);
    B = min(N,B);
    return {A,B};
}

Compilation message (stderr)

communication.cpp: In function 'std::pair<int, int> sendtrit(int)':
communication.cpp:33:18: warning: 'a' may be used uninitialized in this function [-Wmaybe-uninitialized]
   33 |     return ans[(a<<2)+(b<<1)+c];
      |                ~~^~~~
communication.cpp:33:29: warning: 'c' may be used uninitialized in this function [-Wmaybe-uninitialized]
   33 |     return ans[(a<<2)+(b<<1)+c];
      |                ~~~~~~~~~~~~~^~
communication.cpp:33:25: warning: 'b' may be used uninitialized in this function [-Wmaybe-uninitialized]
   33 |     return ans[(a<<2)+(b<<1)+c];
      |                       ~~^~~~

• Subtask 1: 15 / 15
• Subtask 2: 0 / 85