Submission #303767

#	Time	Username	Problem	Language	Result	Execution time	Memory
303767		imeimi2000	Counting Mushrooms (IOI20_mushrooms)	C++17	100 / 100	13 ms	412 KiB

mushrooms

#include "mushrooms.h"
#include <bits/stdc++.h>

using namespace std;

static int ask(string s, vector<int> A, const vector<int> &z, const vector<int> &o) {
    vector<int> q;
    int iz = 0, io = 0;
    for (char c : s) {
        if ('0' <= c && c <= '9') {
            q.push_back(A[c - '0']);
        }
        else if (c == 'A') {
            q.push_back(z[iz++]);
        }
        else {
            q.push_back(o[io++]);
        }
    }
    return use_machine(q);
}

int calc(string s, int x) {
    for (int i = 0; i < int(s.length()); ++i) {
        if ('0' <= s[i] && s[i] <= '9') {
            s[i] = 'A' + ((x >> s[i] - '0') & 1);
        }
    }
    int ret = 0;
    for (int i = 1; i < int(s.length()); ++i) {
        ret += s[i - 1] != s[i];
    }
    return ret;
}

int count_mushrooms(int n) {
    const string start = "0A1A2A3A4";
    string qu[9];
    qu[0] = "01234A"; // (1, 0)
    qu[1] = "01234A"; // (1, 0)
    qu[2] = "012B3B4A"; // (1, 2)
    qu[3] = "0124AAB3B"; // (2, 2)
    qu[4] = "014A23BA"; // (2, 1)
    qu[5] = "0124A3A"; // (2, 0)
    qu[6] = "012A3A4A"; // (3, 0)
    qu[7] = "01234A"; // (1, 0)
    qu[8] = "01234A"; // (1, 0)
    const int B = 100;
    vector<int> A[2];
    A[0].push_back(0);
    int i = 1;
    for (; i < n && int(max(A[0].size(), A[1].size())) < 2; ++i) {
        A[use_machine({ 0, i })].push_back(i);
    }
    for (; i + 1 < n && int(max(A[0].size(), A[1].size())) < B; ) {
        if (i + 4 < n && int(max(A[0].size(), A[1].size())) >= 4 && int(min(A[0].size(), A[1].size())) >= 2) {
            vector<int> X;
            while (int(X.size()) < 5) X.push_back(i++);
            int b = A[0].size() > A[1].size() ? 0 : 1;
            int ret1 = ask(start, X, A[b], A[1 - b]);
            int ret2 = ask(qu[ret1], X, A[b], A[1 - b]);
            int bit;
            for (bit = 0; calc(start, bit) != ret1 || calc(qu[ret1], bit) != ret2; ++bit);
            if (b) bit = 31 - bit;
            for (int i = 0; i < 5; ++i) {
                A[(bit >> i) & 1].push_back(X[i]);
            }
        }
        else if (int(A[0].size()) >= 2) {
            int ret = use_machine({ A[0][0], i, A[0][1], i + 1 });
            A[ret % 2].push_back(i + 1);
            A[ret / 2].push_back(i);
            i += 2;
        }
        else {
            int ret = use_machine({ A[1][0], i, A[1][1], i + 1 });
            A[1 - ret % 2].push_back(i + 1);
            A[1 - ret / 2].push_back(i);
            i += 2;
        }
    }
    int ret = A[0].size();
    for (; i < n; ) {
        if (A[0].size() > A[1].size()) {
            vector<int> q1;
            for (; i < n && q1.size() < A[0].size(); ++i) q1.push_back(i);
            vector<int> q;
            for (int i = 0; i < int(q1.size()); ++i) {
                q.push_back(A[0][i]);
                q.push_back(q1[i]);
            }
            int u = use_machine(q);
            A[u % 2].push_back(q1.back());
            ret += int(q1.size()) - (u + 1) / 2;
        }
        else {
            vector<int> q1;
            for (; i < n && q1.size() < A[1].size(); ++i) q1.push_back(i);
            vector<int> q;
            for (int i = 0; i < int(q1.size()); ++i) {
                q.push_back(A[1][i]);
                q.push_back(q1[i]);
            }
            int u = use_machine(q);
            A[1 - u % 2].push_back(q1.back());
            ret += (u + 1) / 2;
        }
    }
    return ret;
}

Compilation message (stderr)

mushrooms.cpp: In function 'int calc(std::string, int)':
mushrooms.cpp:26:38: warning: suggest parentheses around '-' inside '>>' [-Wparentheses]
   26 |             s[i] = 'A' + ((x >> s[i] - '0') & 1);

• Subtask 1: 100 / 100