Submission #500420

#	Time	Username	Problem	Language	Result	Execution time	Memory
500420		CatalinT	Unscrambling a Messy Bug (IOI16_messy)	C++17	100 / 100	2 ms	464 KiB

messy

#include <vector>
#include <iostream>
#include <string>
#include <numeric>
#include <cassert>

using namespace std;

#include "messy.h"

int W, R;

void rec_write(int l, int r, int n) {
    // use sz - 1 ones and 1 0
    // use the first half of the range

    int sz = r - l + 1;

    // cerr << "write: " << sz << " -> " << l << " " << r << "\n";

    if (sz == 1) {
        return;
    }

    int m = (l + r) >> 1;

    string t = string(n, '0');
    for (int i = l; i <= r; i++)
        t[i] = '1';

    for (int i = l; i <= m; i++) {
        auto q = t; 
        q[i] = '0';

        // cerr << q << "\n";

        W++;
        add_element(q);
    }

    rec_write(l, m, n);
    rec_write(m + 1, r, n); 
}

vector<int> sol;

void rec_read(int l, int r, const vector<int>& idx, int n) {
    // Range l ... r is known to be in indexes idx
    int sz = r - l + 1;

    // cerr << "read: " << sz << " -> " << l << " " << r << "\n";

    if (sz == 1) {
        // At this point we should know the answer for l .. r -> idx[0]
        assert(idx.size() == 1);
        sol[l] = idx[0];
        return;
    }

    int m = (l + r) >> 1;

    // 

    string t = string(n, '0');
    for (int i : idx)
        t[i] = '1';

    vector<int> left_idx;
    vector<int> right_idx;

    for (int i : idx) {
        auto q = t; 
        q[i] = '0';

        // cerr << q << "\n";

        R++;
        if (check_element(q)) {
            left_idx.push_back(i);
        } else {
            right_idx.push_back(i);
        }
    }

    rec_read(l, m, left_idx, n);
    rec_read(m + 1, r, right_idx, n); 
}

std::vector<int> restore_permutation(int n, int w, int r) {
    rec_write(0, n - 1, n);
    // cerr << "compiled\n";
    compile_set();

    vector<int> idx(n);
    iota(idx.begin(), idx.end(), 0);
    sol.assign(n, -1);
    rec_read(0, n - 1, idx, n);

    // cerr << "W: " << W << " R: " << R << "\n";

    // reverse
    vector<int> res(n);
    for (auto & x : sol)
        res[sol[x]] = x;

    return res;
}

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