Submission #133904

#	Time	Username	Problem	Language	Result	Execution time	Memory
133904		KieranHorgan	Cave (IOI13_cave)	C++17	100 / 100	1151 ms	640 KiB

cave

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

void exploreCave(int N) {
	int switchOfDoorXIsKnown[N];
	int doorOfSwitchXIsKnown[N];
	int posOfSwitch[N];
	memset(switchOfDoorXIsKnown, -1, sizeof(switchOfDoorXIsKnown));
	memset(doorOfSwitchXIsKnown, -1, sizeof(doorOfSwitchXIsKnown));
	memset(posOfSwitch, -1, sizeof(posOfSwitch));

	int toGuess[N];
	for(int i = 0; i < N; i++) {
		for(int j = 0; j < N; j++)
			if(doorOfSwitchXIsKnown[j] == -1)
				toGuess[j] = 0;
			else
				toGuess[j] = posOfSwitch[j];

		bool offIsDown = tryCombination(toGuess) == i;

		int lo = 0;
		int hi = N-1;
		while(lo != hi) {
			int mid = (lo+hi)/2;
			for(int j = 0; j < N; j++)
				if(doorOfSwitchXIsKnown[j] == -1) {
					if(j <= mid)
						toGuess[j] = 0;
					else
						toGuess[j] = 1;
				} else {
					toGuess[j] = posOfSwitch[j];
				}
			if(offIsDown == (tryCombination(toGuess) == i))
				hi = mid;
			else
				lo = mid+1;
		}
		switchOfDoorXIsKnown[i] = lo;
		doorOfSwitchXIsKnown[lo] = i;
		posOfSwitch[lo] = offIsDown;
	}
	answer(posOfSwitch, doorOfSwitchXIsKnown);
}

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