Submission #703321

#	Time	Username	Problem	Language	Result	Execution time	Memory
703321		SamNguyen	Cave (IOI13_cave)	C++14	51 / 100	176 ms	524 KiB

cave

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

const int MAX = 5000 + 7;
int swit[MAX], door[MAX];

namespace Subtask1 {
    bool exploreCave(int N) {
        iota(door, door + N, 0);
        fill(swit, swit + N, 0);

        int cnt = 0;
        while (cnt <= N) {
            int i = tryCombination(swit);
            if (i == -1) {
                answer(swit, door);
                return true;
            }
            swit[i] ^= 1;
            cnt++;
        }

        return false;
    }
}

namespace Subtask2 {
    bool exploreCave(int N) {
        fill(swit, swit + N, 0);

        for (int i = 0; i < N; i++) {
            swit[i] = 1;
            door[i] = tryCombination(swit);
            swit[i] = 0;
        }
        answer(swit, door);

        return true;
    }
}

namespace Subtask3 {
    bool exploreCave(int N) {
        mt19937 rnd(20050701);
        generate(swit, swit + N, [&]() {
            return rnd() & 1;
        });

        int p = tryCombination(swit);
        while (p != -1) {
            for (int i = 0; i < N; i++) {
                swit[i] ^= 1;
                int p2 = tryCombination(swit);
                if (p2 > p or p2 == -1) {
                    p = p2;
                    break;
                }
                swit[i] ^= 1;
            }
        }

        for (int i = 0; i < N; i++) {
            swit[i] ^= 1;
            door[i] = tryCombination(swit);
            swit[i] ^= 1;
        }
        answer(swit, door);

        return true;
    }
}

namespace Subtask4 {
    mt19937 rnd(20050701);
    bool is_fixed[MAX];

    int INIT_COMB;

    pair<int, int> find_switch_for_door(int i, int l, int r) {
        if (l == r) {
            if (not is_fixed[r])
                swit[r] ^= 1;
            int p = INIT_COMB = tryCombination(swit);
//            cerr << "try " << i << " " << l << " " << r << " -> " << p << endl;
            if (not is_fixed[r])
                swit[r] ^= 1;

            if (p == i)
                return make_pair(swit[r], r);
            return make_pair(swit[r] ^ 1, r);
        }

        int p1 = INIT_COMB;
        int m = (l + r) >> 1;
        for (int x = l; x <= m; x++) if (not is_fixed[x])
            swit[x] ^= 1;

        int p2 = tryCombination(swit);
        for (int x = l; x <= m; x++) if (not is_fixed[x])
            swit[x] ^= 1;

        if ((p1 == i) xor (p2 == i))
            return find_switch_for_door(i, l, m);
        return find_switch_for_door(i, m + 1, r);
    }

    bool exploreCave(int N) {
        fill(is_fixed, is_fixed + N, false);

        for (int i = 0; i < N; i++) {
            INIT_COMB = tryCombination(swit);

            int res, p;
            tie(res, p) = find_switch_for_door(i, 0, N - 1);
            door[p] = i;
            swit[p] = res;
            is_fixed[p] = true;
        }

        answer(swit, door);
        return true;
    }
}

void exploreCave(int N) {
    Subtask4::exploreCave(N);
}

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