Submission #876840

#TimeUsernameProblemLanguageResultExecution timeMemory
876840KanonCounting Mushrooms (IOI20_mushrooms)C++14
94.17 / 100
6 ms1044 KiB
#include <bits/stdc++.h> #include "mushrooms.h" using namespace std; int magic = 50; const int bound = 226; mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count()); // generate random number between l, r : uniform_int_distribution<long long>(l, r)(rng) // random shuffle : shuffle(.begin(), .end(), rng) int count_mushrooms(int n) { if (n <= bound + 1) { int ret = 1; for (int i = 1; i < n; i++) { ret += use_machine({0, i}) ^ 1; } return ret; } vector<int> a(n, -1); a[0] = 0; vector<int> order(2 * magic); iota(order.begin(), order.end(), 1); int cnt = 2 * magic + 1; vector<int> zeros, ones; zeros.push_back(0); while (zeros.size() < 3 && ones.size() < 3) { int st = use_machine({0, cnt++}); a[cnt - 1] = a[0] ^ (st & 1); if (a[cnt - 1] == 0) zeros.push_back(cnt - 1); else ones.push_back(cnt - 1); } int p1, p2, p3, bit; if (zeros.size() >= 3) { p1 = zeros[0], p2 = zeros[1], p3 = zeros[2], bit = 0; } else { p1 = ones[0], p2 = ones[1], p3 = ones[2], bit = 1; } zeros.clear(); ones.clear(); auto calc = [&](vector<int> d) { vector<int> que = {p1, d[0], p2}; if (d.size() > 1) { que.push_back(d[1]); que.push_back(p3); } que.push_back(cnt++); int st = use_machine(que); a[cnt - 1] = bit ^ (st & 1); st -= st & 1; st >>= 1; if (bit == 1) st = d.size() - st; return st; }; function<void(vector<int>)> solve = [&](vector<int> pos) { if (pos.empty()) return; if (pos.size() == 1) { int p = pos[0]; a[p] = calc({p}); return; } shuffle(pos.begin(), pos.end(), rng); vector<int> L, R; for (int i = 0; i + 1 < (int) pos.size(); i += 2) { int sum = calc({pos[i], pos[i + 1]}); if (sum == 1) { L.push_back(pos[i]); R.push_back(pos[i + 1]); } else { a[pos[i]] = a[pos[i + 1]] = sum >> 1; } } if (pos.size() & 1) { int p = pos.back(); a[p] = calc({p}); } solve(L); for (int i = 0; i < (int) L.size(); i++) { int l = L[i], r = R[i]; assert(a[l] != -1); a[r] = a[l] ^ 1; } }; solve(order); int ret = 0; for (int i = 0; i < n; i++) { ret += a[i] == 0; if (a[i] == 0) zeros.push_back(i); if (a[i] == 1) ones.push_back(i); } while (cnt < n) { int len = min(n - cnt, (int) max(zeros.size(), ones.size())); vector<int> ids = zeros.size() >= ones.size() ? zeros : ones; vector<int> que; for (int i = 0; i < len; i++) { que.push_back(ids[i]); que.push_back(cnt++); } int st = use_machine(que); if (ids == ones) { a[cnt - 1] = 1 ^ (st & 1); ret += a[cnt - 1] == 0; st -= a[cnt - 1] == 0; if (a[cnt - 1] == 0) zeros.push_back(cnt - 1); else ones.push_back(cnt - 1); assert(st % 2 == 0); ret += st >> 1; } else { a[cnt - 1] = 0 ^ (st & 1); ret += a[cnt - 1] == 0; st -= a[cnt - 1] == 1; if (a[cnt - 1] == 0) zeros.push_back(cnt - 1); else ones.push_back(cnt - 1); assert(st % 2 == 0); ret += (len - 1) - (st >> 1); } } return ret; }
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