Submission #1217027

#	Time	Username	Problem	Language	Result	Execution time	Memory
1217027		lukasuliashvili	Cave (IOI13_cave)	C++20	0 / 100	546 ms	516 KiB

cave

#include "cave.h"
#include <vector>
using namespace std;

void exploreCave(int N) {
    vector<int> correctState(N, 0);    // correct switch positions
    vector<int> switchToDoor(N, -1);   // which door each switch controls
    vector<bool> visited(N, false);    // switches that are already assigned
    vector<int> test(N, 0);            // temporary array for testing

    for (int d = 0; d < N; ++d) {
        // Binary search to find which switch controls door d
        int lo = 0, hi = N - 1;
        int controllingSwitch = -1;

        while (lo <= hi) {
            int mid = (lo + hi) / 2;

            // Set unknown switches from lo to mid to 1, others to 0
            for (int i = 0; i < N; ++i) {
                if (visited[i]) {
                    test[i] = correctState[i];  // already known
                } else if (i >= lo && i <= mid) {
                    test[i] = 1;
                } else {
                    test[i] = 0;
                }
            }

            int res = tryCombination(test.data());

            if (res == d || res == -1) {
                // One of [lo..mid] controls door d
                hi = mid - 1;
            } else {
                lo = mid + 1;
            }
        }

        controllingSwitch = lo;

        // Figure out the correct position for the controlling switch
        // Set it to 0 first
        for (int i = 0; i < N; ++i)
            test[i] = visited[i] ? correctState[i] : 0;
        test[controllingSwitch] = 0;
        int res0 = tryCombination(test.data());

        correctState[controllingSwitch] = (res0 == d || res0 == -1) ? 0 : 1;
        switchToDoor[controllingSwitch] = d;
        visited[controllingSwitch] = true;
    }

    answer(correctState.data(), switchToDoor.data());
}

• Subtask 1: 0 / 12
• Subtask 2: 0 / 13
• Subtask 3: 0 / 21
• Subtask 4: 0 / 30
• Subtask 5: 0 / 24