Submission #1197287

#	Time	Username	Problem	Language	Result	Execution time	Memory
1197287		dong_gas	Counting Mushrooms (IOI20_mushrooms)	C++20	0 / 100	0 ms	424 KiB

mushrooms

#include <bits/extc++.h>
using namespace std;
int use_machine(vector<int> x);

int f(int n) {
    int b = 0;
    for (int i = 1; i + 1 < n; i += 2) b += use_machine({i, 0, i + 1});
    if ((n & 1) == 0) b += use_machine({0, n - 1});
    return n - b;
}

// sqrt(20000) = 141.xx
vector<int> a[2] = {{0}, {}};
int idx = 1, k = 79;


// rule: https://oj.uz/submission/303279 ....
map<vector<int>, string> prec1 = {{{}, "A0B0C0DE"},   {{1}, "CED"},   {{2}, "DBE0A"}, {{3}, "CB0E0DA1"},
                                  {{4}, "D0A0E0CB1"}, {{5}, "DBCE1"}, {{6}, "CED"}};

map<vector<int>, string> prec2 = {{{}, "ABCDE0"},   {{1}, "B0"},        {{1, 1}, "EADC"}, {{2}, "CB0D"},
                                  {{2, 1}, "EADB"}, {{2, 2}, "DAE0CB"}, {{3}, "CB0D"},    {{3, 1}, "EDB0"},
                                  {{3, 2}, "AED"},  {{3, 3}, "ED"},     {{4}, "B0"},      {{4, 1}, "0EACD"}};

int chk(string& s, int state) {
    int ret = 0;
    for (char& c: s) {
        if ('A' <= c && c <= 'Z') c = (char) ('0' + ((state) >> (c - 'A') & 1));
    }
    for (int i = 1; i < s.size(); i++) ret += s[i - 1] != s[i];
    return ret;
}

int count_mushrooms(int n) {
    if (n <= 450) return f(n);
    int ret = 0;
    while (idx < n) {
        int t = a[0].size() < a[1].size();
        if (n - idx < 5 || a[t].size() >= k) {
            int t = (a[0].size() < a[1].size());
            vector<int> query, &c = a[t];
            int qcnt = 0;
            for (int i = 0; i < c.size() && idx < n; i++) query.push_back(c[i]), query.push_back(idx++), qcnt++;
            // for (auto qq: q) cout << qq << ' ';
            // cout << endl;
            int cnt = use_machine(query);
            int p = cnt / 2 + (cnt & 1);
            if (cnt & 1) a[t ^ 1].push_back(idx - 1), ret += p;
            else a[t].push_back(idx - 1), ret += qcnt - p;
        }
        else {  // 다 쳐넣음
            map<vector<int>, string>& rule = a[t].size() >= 3 && a[t ^ 1].size() >= 1 ? prec1 : prec2;
            vector<int> record, cnt(2, 0), valid(32, 1);
            for (int i = 0; i < 5; i++) record.push_back(i + idx);
            while (rule.count(record)) {
                vector<int> query;
                for (char c: record) {
                    if (c == '0' || c == '1') query.push_back(a[(c - '0') ^ 1][cnt[(c - '0') ^ 1]]++);
                    else query.push_back(idx + (c - 'A'));
                }
                int q = use_machine(query);
                record.push_back(q);
                for (int state = 0; state < 32; state++) {
                    if (chk(rule[record], state) != q) valid[state] = 0;
                }
            }
            for (int state = 0; state < 32; state++) {
                if (valid[state]) {
                    for (int i = 0; i < 5; i++) {
                        a[(state >> i & 1) ^ t].push_back((idx++) + i);
                        ret += ((state >> i & 1) ^ t) == 0;
                    }
                    break;
                }
            }
        }
    }
    return ret;
}

• Subtask 1: 0 / 100