| # | 제출 시각 | 아이디 | 문제 | 언어 | 결과 | 실행 시간 | 메모리 |
|---|---|---|---|---|---|---|---|
| 734682 | rainliofficial | 콤보 (IOI18_combo) | C++11 | 0 ms | 0 KiB |
이 제출은 이전 버전의 oj.uz에서 채점하였습니다. 현재는 제출 당시와는 다른 서버에서 채점을 하기 때문에, 다시 제출하면 결과가 달라질 수도 있습니다.
#include "combo.h"
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
template<class T> bool ckmin(T& a, const T& b) { return b < a ? a = b, 1 : 0; }
template<class T> bool ckmax(T& a, const T& b) { return a < b ? a = b, 1 : 0; }
#define sz(x) (int)x.size()
#define all(x) begin(x), end(x)
/*
Date: 2023/05/02 11:56
Problem Link:
Topic(s):
Reflection:
Solution Notes:
We can obtain the first character in 2 moves:
guess AB
if (>=1): then A or B
else: then X or Y
Then we want to be able to determine 3 characters for every 1 query.
Notice we get 4N queries, so it has something to do with 4 possibilities with every query.
I initally didn't utilize the 4N constraint, and I thought about queries 2 new characters every time.
If we have X, we query XAB: I hoped this would amortize to N queries. However, this would still end up
with the issue of having to determine > 2 possibilities with 1 query.
Another key constraint is that the first character in S cannot appear again. We can thus use the first character,
(e.g. X), to split differrent strings that we want to query.
Consider the following method:
X___ X___ X___ X___
What can we put in each of the empty spaces to for sure know the next character?
XA XBA XBB XBC
If A is the next character -> return 1
If B is next char -> return 2
If Y is next character -> 0
*/
const int MAXN = 2e5+5, INF = 1e9;
int n;
vector<char> c = {'A', 'B', 'X', 'Y'}, cc;
namespace {
constexpr int MAX_N = 2000;
constexpr int MAX_NUM_MOVES = 8000;
int N;
std::string S;
int num_moves;
void wrong_answer(const char *MSG) {
printf("Wrong Answer: %s\n", MSG);
exit(0);
}
}
int press(std::string p) {
if (++num_moves > MAX_NUM_MOVES) {
wrong_answer("too many moves");
}
int len = p.length();
if (len > 4 * N) {
wrong_answer("invalid press");
}
for (int i = 0; i < len; ++i) {
if (p[i] != 'A' && p[i] != 'B' && p[i] != 'X' && p[i] != 'Y') {
wrong_answer("invalid press");
}
}
int coins = 0;
for (int i = 0, j = 0; i < len; ++i) {
if (j < N && S[j] == p[i]) {
++j;
} else if (S[0] == p[i]) {
j = 1;
} else {
j = 0;
}
coins = std::max(coins, j);
}
return coins;
}
string guess_sequence(int n){
string s;
auto add1 = [&](){
int x = press(s + "AB");
if (x > sz(s)){
// start with A
if (press(s + 'A') > sz(s)) s += 'A';
else s += "B";
}else{
if (press(s + 'X') > sz(s)) s += "X";
else s += "Y";
}
};
add1();
for (char j : c) if (j != s[0]) cc.push_back(j);
for (int i=1; i<n-1; i++){
string q;
q += s + cc[0];
for (int j=0; j<3; j++){
q += s + cc[1] + cc[j];
}
int x = press(q);
if (x == sz(s)) s += cc[2];
else if (x == sz(s) + 1) s += cc[0];
else if (x == sz(s) + 2) s += cc[1];
else assert(false);
}
add1();
return s;
}
// int main(){
// // cin.tie(0); ios_base::sync_with_stdio(0);
// // freopen("file.in", "r", stdin);
// // freopen("file.out", "w", stdout);
// S = "XABBABA";
// N = sz(S);
// num_moves = 0;
// std::string answer = guess_sequence(N);
// if (answer != S) {
// cout << answer << "\n";
// wrong_answer("wrong guess");
// exit(0);
// }
// printf("Accepted: %d\n", num_moves);
// }