Submission #1003582

#	Time	Username	Problem	Language	Result	Execution time	Memory
1003582		toast12	Cave (IOI13_cave)	C++14	100 / 100	564 ms	608 KiB

cave

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

void exploreCave(int N) {
    int s[N], d[N];
    for (int i = 0; i < N; i++) {
        s[i] = 0;
        d[i] = -1;
    }
    vector<bool> found(N);
    // iterate over all doors and find out which switch opens the ith door
    for (int i = 0; i < N; i++) {
        // find which switch unlocks door i
        // first find the position in which door i gets unlocked
        int x = tryCombination(s);
        if (x == -1)
            x = i+1;
        int pos = 0;
        if (x <= i) 
            pos = 1;
        int lo = 0, hi = N-1;
        while (lo < hi) {
            int mid = lo+(hi-lo)/2;
            // check left half
            for (int j = lo; j <= mid; j++) {
                if (!found[j])
                    s[j] = pos;
            }
            for (int j = mid+1; j < N; j++) {
                if (!found[j])
                    s[j] = 1-pos;
            }
            x = tryCombination(s);
            for (int j = 0; j < N; j++) {
                if (!found[j])
                    s[j] = 0;
            }
            if (x == -1)
                x = i+1;
            if (x > i) {
                hi = mid;
            }
            else {
                lo = mid+1;
            }
        }
        d[hi] = i;
        s[hi] = pos;
        found[hi] = true;
        // for (int j = 0; j < N; j++) {
        //     if (found[j]) {
        //         cout << j << ": " << s[j] << '\n';
        //     }
        // }
    }
    answer(s, d);
}

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