Submission #648622

#	Time	Username	Problem	Language	Result	Execution time	Memory
648622		lorenzoferrari	Martian DNA (IOI16_dna)	C++17	100 / 100	13 ms	980 KiB

dna

#include <bits/stdc++.h>
using namespace std;

bool make_test(string s);

unordered_map<string, bool> memo;

bool ask(const string& s) {
    if (memo.find(s) != memo.end()) {
        return memo[s];
    } else {
        return memo[s] = make_test(s);
    }
}

static string nsqrtn(int n, string cur) {
    constexpr size_t K = 100;
    string prv = cur;
    while (cur.size() != n) {
        if (ask(cur + "1")) {
            cur = prv = cur + "1";
        } else {
            cur += "0";
        }
        if (cur.size() - prv.size() > K) {
            if (ask(cur)) {
                prv = cur;
            } else {
                break;
            }
        }
    }
    while ((int)prv.size() != n && (ask(prv + "0") || ask(prv + "1"))) {
        if (ask(prv + "0")) {
            prv += "0";
        } else {
            prv += "1";
        }
    }
    while ((int)prv.size() != n) {
        if (ask("0" + prv)) {
            prv = "0" + prv;
        } else {
            prv = "1" + prv;
        }
    }
    return prv;
}

string analyse(int n, int t) {
if (ask(string(200, '0'))) {
        return nsqrtn(n, string(200, '0'));
    }
    int l = 0, r = 200;
    while (r - l > 1) {
        int m = (l + r) / 2;
        if (ask(string(m, '0'))) {
            l = m;
        } else {
            r = m;
        }
    }
    string cur = string(l, '0');
    string prv = cur;
    while ((int)cur.size() != n && (int)(cur.size() - prv.size()) <= l) {
        if (ask(cur + "1")) {
            cur = prv = cur + "1";
        } else {
            cur += "0";
        }
    }
    while (ask(prv + "0")) {
        prv += "0";
    }
    while ((int)prv.size() != n) {
        if (ask("0" + prv)) {
            prv = "0" + prv;
        } else {
            prv = "1" + prv;
        }
    }
    return prv;
}

Compilation message (stderr)

dna.cpp: In function 'std::string nsqrtn(int, std::string)':
dna.cpp:19:23: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   19 |     while (cur.size() != n) {
      |            ~~~~~~~~~~~^~~~
grader.cpp: In function 'bool make_test(std::string)':
grader.cpp:14:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   14 |  for (int i = 0; i < p.size(); i++) {
      |                  ~~^~~~~~~~~~
grader.cpp:23:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   23 |  for (int i = 1; i <= ss.size(); i++) {
      |                  ~~^~~~~~~~~~~~
grader.cpp:28:13: warning: comparison of integer expressions of different signedness: '__gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type' {aka 'int'} and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   28 |   if (pr[i] == p.size()) {

• Subtask 1: 11 / 11
• Subtask 2: 25 / 25
• Subtask 3: 64 / 64