Submission #607675

#	Time	Username	Problem	Language	Result	Execution time	Memory
607675		jairRS	Cave (IOI13_cave)	C++17	0 / 100	2 ms	852 KiB

cave

#include "cave.h"
#include <bits/stdc++.h>
#define all(s) s.begin(), s.end()
using namespace std;
using vi = vector<int>;

const int MAXN = 5'000;
int switches[MAXN];

// door triggered by switchID
int door[MAXN];

int gN;

// returns N instead of -1 when all doors are open
int getLastDoor()
{
    int lastDoor = tryCombination(switches);
    if (lastDoor == -1)
        lastDoor = gN;
    return lastDoor;
}

void flipSwitches(int i, int j, vi &ids)
{
    for (int k = i; k <= j; k++)
        switches[ids[k]] = !switches[ids[k]];
}

void exploreCave(int N)
{
    gN = N;

    vi unassignedSwitches;
    for (int i = 0; i < N; i++)
        unassignedSwitches.push_back(i);

    // doors up to curDoor EXCEPT curDoor are open
    for (int curDoor = 0; curDoor < N; curDoor++)
    {
        int doorOpen = getLastDoor() > curDoor;

        int respSwitch;
        int lo = 0, hi = unassignedSwitches.size() - 1;
        while (lo < hi)
        {
            int mid = (lo + hi) / 2;
            flipSwitches(lo, mid, unassignedSwitches);

            int lastDoor = getLastDoor();
            bool check = false;
            if (doorOpen)
            {
                if (lastDoor == curDoor)
                    check = true;
            }
            else if (lastDoor > curDoor)
                check = true;

            if (check)
                hi = mid;
            else
                lo = mid + 1;

            flipSwitches(lo, mid, unassignedSwitches);
        }
        respSwitch = lo;
        unassignedSwitches.erase(find(all(unassignedSwitches), respSwitch));
        door[respSwitch] = curDoor;

        if (!doorOpen)
            switches[respSwitch] = !switches[respSwitch];
    }

    answer(switches, door);
}

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