Submission #524261

#	Time	Username	Problem	Language	Result	Execution time	Memory
524261		tabr	Unscrambling a Messy Bug (IOI16_messy)	C++17	100 / 100	2 ms	460 KiB

messy

#include <bits/stdc++.h>
using namespace std;
#ifdef tabr
#include "library/debug.cpp"
#else
#define debug(...)
#endif

#ifdef tabr
function<void(string)> add_element;
function<void()> compile_set;
function<bool(string)> check_element;
#else
#include "messy.h"
#endif

vector<int> restore_permutation(int n, int, int) {
    int k = __builtin_ctz(n);
    for (int t = k - 1; t >= 0; t--) {
        for (int i = 0; i < n; i++) {
            if (i & (1 << t)) {
                string s(n, '0');
                s[i] = '1';
                for (int j = 0; j < n; j++) {
                    if ((i ^ j) >> (t + 1)) {
                        s[j] = '1';
                    }
                }
                add_element(s);
                debug(s);
            }
        }
    }
    compile_set();
    vector<int> p(n);
    function<void(vector<int>)> dfs = [&](vector<int> a) {
        // debug(a.size());
        if (a.size() == 1) {
            return;
        }
        int sz = (int) a.size();
        string s(n, '1');
        for (int i : a) {
            s[i] = '0';
        }
        vector<int> b, c;
        for (int i : a) {
            s[i] = '1';
            if (check_element(s)) {
                p[i] |= sz >> 1;
                b.emplace_back(i);
            } else {
                c.emplace_back(i);
            }
            s[i] = '0';
        }
        dfs(b);
        dfs(c);
    };
    vector<int> a(n);
    iota(a.begin(), a.end(), 0);
    dfs(a);
    return p;
}

#ifdef tabr
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n;
    cin >> n;
    mt19937 rng((unsigned int) chrono::steady_clock::now().time_since_epoch().count());
    vector<int> p(n);
    iota(p.begin(), p.end(), 0);
    shuffle(p.begin(), p.end(), rng);
    vector<string> t;
    int cnt0 = 0;
    int cnt1 = 0;
    add_element = [&](string x) {
        cnt0++;
        t.emplace_back(x);
    };
    compile_set = [&]() {
        for (string& x : t) {
            string y = x;
            for (int i = 0; i < n; i++) {
                x[p[i]] = y[i];
            }
        }
        sort(t.begin(), t.end());
    };
    check_element = [&](string x) {
        cnt1++;
        return binary_search(t.begin(), t.end(), x);
    };
    auto q = restore_permutation(n, 0, 0);
    debug(p);
    debug(q);
    for (int i = 0; i < n; i++) {
        assert(q[p[i]] == i);
    }
    debug(cnt0, cnt1);
    return 0;
}
#endif

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