Submission #658242

#	Time	Username	Problem	Language	Result	Execution time	Memory
658242		benjaminkleyn	Unscrambling a Messy Bug (IOI16_messy)	C++17	100 / 100	2 ms	468 KiB

messy

#include <bits/stdc++.h>
#include "messy.h"
using namespace std;
typedef long long ll;

vector<int> res;
void find(int l, int r, vector<int> idx, int n)
{
    /* // debug
    cout << "(l, r) = (" << l << ", " << r << ")\n";
    cout << "idx = [";
    for (int x : idx)
        cout << x << " ";
    cout << "]\n";
    */

    if (l == r)
    {
        res[idx[0]] = l;
        return;
    }
    // assuming we know the indices in idx are mapped to the range [l, r]
    vector<int> left_idx, right_idx;
    for (int i : idx)
    {
        string s(n, '1');
        for (int j : idx)
            if (j != i)
                s[j] = '0';

        if (check_element(s))
            left_idx.push_back(i);
        else
            right_idx.push_back(i);
    }
    int m = (l + r) / 2;
    find(l, m, left_idx, n);
    find(m + 1, r, right_idx, n);
}


vector<int> restore_permutation(int n, int w, int r) 
{
    // consider a number of the form
    //
    // 10000000
    // 01000000
    // 00100000
    // 00010000
    //
    // or something like that, so we can halve the searching space.

    for (int k = 1; k < n; k *= 2)
    {
        // cout << k << '\n';
        for (int i = 0; i < n; i += 2 * k)
        {
            string s(n, '1');
            for (int j = i; j < i + 2 * k; j++)
                s[j] = '0';
            for (int j = i; j < i + k; j++)
            {
                s[j] = '1';
                // cout << s << '\n';
                add_element(s);
                s[j] = '0';
            }
        }
    }

    compile_set();

    vector<int> idx(n);
    for (int i = 0; i < n; i++)
        idx[i] = i;

    res.resize(n);
    find(0, n - 1, idx, n);

    return res;
}

• Subtask 1: 20 / 20
• Subtask 2: 18 / 18
• Subtask 3: 11 / 11
• Subtask 4: 21 / 21
• Subtask 5: 30 / 30