# | Time | Username | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
303279 | model_code | Counting Mushrooms (IOI20_mushrooms) | C++17 | 10 ms | 552 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
// decision-tree-endagorion
/*
* Model solution for task mushrooms
*
* Author: Mikhail Tikhomirov
*/
#include "mushrooms.h"
#include <vector>
#include <string>
#include <map>
#include <cassert>
#define mp make_pair
#define mt make_tuple
#define fi first
#define se second
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define forn(i, n) for (int i = 0; i < (int)(n); ++i)
#define for1(i, n) for (int i = 1; i <= (int)(n); ++i)
#define ford(i, n) for (int i = (int)(n) - 1; i >= 0; --i)
#define fore(i, a, b) for (int i = (int)(a); i <= (int)(b); ++i)
using namespace std;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<pii> vpi;
typedef vector<vi> vvi;
typedef long long i64;
typedef vector<i64> vi64;
typedef vector<vi64> vvi64;
typedef pair<i64, i64> pi64;
typedef double ld;
template<class T> bool uin(T &a, T b) { return a > b ? (a = b, true) : false; }
template<class T> bool uax(T &a, T b) { return a < b ? (a = b, true) : false; }
vi labels;
vvi lst;
int K = 110;
int ans;
void label(int p, int z) {
// cerr << p << ' ' << z << '\n';
labels[p] = z;
lst[z].pb(p);
if (!z) ++ans;
}
int p;
int z;
vi toQ;
string subs(string s, int mask) {
for (char &c: s) if (c >= 'A' && c <= 'Z') c = (char)('0' + ((mask >> (c - 'A')) & 1));
return s;
}
int eval(const string &s) {
int ret = 0;
forn(i, (int)s.size() - 1) ret += int(s[i] != s[i + 1]);
return ret;
}
int query(string s) {
vi v;
vi ptr(2);
for (char c: s) {
if (c == '0' || c == '1') {
int d = (c - '0') ^ z;
assert(ptr[d] < (int)lst[d].size());
v.pb(lst[d][ptr[d]++]);
} else {
int l = c - 'A';
v.pb(toQ[l]);
}
}
return use_machine(v);
}
map<vi, string> prec1 = {
{{}, "A0B0C0DE"},
{{1}, "CED"},
{{2}, "DBE0A"},
{{3}, "CB0E0DA1"},
{{4}, "D0A0E0CB1"},
{{5}, "DBCE1"},
{{6}, "CED"}
};
map<vi, 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"}
};
void magic(map<vi, string> &m) {
toQ.clear();
forn(i, 5) toQ.pb(p + i);
vi seq;
map<string, int> res;
while (m.count(seq)) {
string s = m[seq];
int x = query(s);
res[s] = x;
seq.pb(x);
}
vi goodM;
forn(mask, 32) {
bool ok = true;
for (auto w: res) ok &= eval(subs(w.fi, mask)) == w.se;
if (ok) goodM.pb(mask);
}
assert(goodM.size() == 1);
int mask = goodM[0];
forn(i, 5) label(p++, ((mask >> i) & 1) ^ z);
}
int count_mushrooms(int n) {
labels = vi(n, -1);
lst = vvi(2);
p = 1;
ans = 0;
label(0, 0);
while (p < n) {
z = lst[0].size() > lst[1].size() ? 0 : 1;
if (n - p < 5 || (int)lst[z].size() >= K) {
vi m;
int i = 0;
while (p < n && i < (int)lst[z].size()) {
m.pb(p++);
m.pb(lst[z][i++]);
}
int x = use_machine(m);
lst[z ^ (x & 1)].pb(m[0]);
x = (x + 1) / 2;
ans += (z ? x : i - x);
} else magic(!lst[z ^ 1].empty() && lst[z].size() >= 3 ? prec1 : prec2);
}
return ans;
}
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