Submission #771350

#	Time	Username	Problem	Language	Result	Execution time	Memory
771350		sadsa	Cave (IOI13_cave)	C++17	100 / 100	247 ms	416 KiB

cave

#include "cave.h"

#include <bits/stdc++.h>
using namespace std;

using ll = long long;
using vi = vector<int>;
using vb = vector<bool>;
using ii = tuple<int, int>;
using vii = vector<ii>;

void flip(vi &levers, vb &lv, int l, int r) {
    for (; l <= r; ++l) {
        if (!lv[l]) levers[l] = 1-levers[l];
    }
}

int findCombo(int doorToFind, vi &levers, vb &lv) {
    int l = 0, r = lv.size()-1;
    int door, mid;

    door = tryCombination(levers.data());

    if (door != doorToFind) {
        flip(levers, lv, l, r);
    }

    while (l != r) {
        if (r-l==1) {
            flip(levers, lv, l, l);

            door = tryCombination(levers.data());
            if (door == doorToFind) { // no change, so right side is correct
                l = r;
            } else { // change, ans=l, flip back
                r = l;
                flip(levers, lv, l, l);
            }

            break;
        }

        mid = (l+r)/2;

        flip(levers, lv, mid, r); // flip right 

        door = tryCombination(levers.data());

        if (door == doorToFind) { // nothing changed, so check left half
            r = mid-1;
        } else { // door changed, so flip back and check right half further
            flip(levers, lv, mid, r);
            l = mid;
        }
    }

    flip(levers, lv, l, l); // open door

    lv[l] = true;

    return l;
}

void exploreCave(int N) {
    vi levers(N, 0);
    vi ltd(N, -1);
    vb lv(N, false);

    for (int door = 0; door < N; ++door) {
        ltd[findCombo(door, levers, lv)] = door;
    }

    answer(levers.data(), ltd.data());
}

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