Submission #1000012

#	Time	Username	Problem	Language	Result	Execution time	Memory
1000012		esomer	Martian DNA (IOI16_dna)	C++17	100 / 100	7 ms	444 KiB

dna

#include <bits/stdc++.h>

using namespace std;

bool make_test(string T);

string buildZeros(int zeros){
    string s = "";
    for(int i = 0; i < zeros; i++) s += '0';
    return s;
}

string analyse(int N, int maxT) {
    int maxZeroes = 0;
    int lo = 1;
    int hi = N;
    while(lo <= hi){
        int mid = (lo + hi) / 2;
        string s = buildZeros(mid);
        if(make_test(s)){
            maxZeroes = mid;
            lo = mid + 1;
        }else hi = mid - 1;
    }
    string suf = buildZeros(maxZeroes);
    int t = 0;
    while(t <= maxZeroes){
        suf += '1';
        if(!make_test(suf)){
            t++;
            suf.pop_back();
            suf += '0';
        }else t = 0;
    }
    //I binary search to find exactly the suffix.
    lo = 1;
    hi = maxZeroes+1; //How many do I erase.
    string nwSuf = suf;
    while(lo <= hi){
        int mid = (lo + hi) / 2;
        string s = suf;
        for(int i = 0; i < mid; i++) s.pop_back();
        if(make_test(s)){
            //This is suffix. I can erase less.
            nwSuf = s;
            hi = mid - 1;
        }else lo = mid + 1;
    }
    suf = nwSuf;
    //Now suf is exactly the suffix.
    while((int)suf.size() < N){
        reverse(suf.begin(), suf.end());
        suf += '1';
        reverse(suf.begin(), suf.end());
        if(!make_test(suf)){
            reverse(suf.begin(), suf.end());
            suf.pop_back();
            suf += '0';
            reverse(suf.begin(), suf.end());
        }
    }
    return suf;
}

Compilation message (stderr)

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