Submission #466461

#	Time	Username	Problem	Language	Result	Execution time	Memory
466461		lemelisk	Palindrome-Free Numbers (BOI13_numbers)	C++14	100 / 100	1 ms	332 KiB

numbers

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
ll dp [10][10][20][2];

string str;
// all: all digits are allowed

ll Calc(int first, int second, int len, bool all)
{
    if (len >= str.length())
    {
        return 1;
    }
    else
    {
        if (dp[first][second][len][all]==-1)
        {
            ll help = 0 ;
            if (all)
            {
                for (int n = 0; n <= 9; n++)
                {
                    if (n != first && n != second)
                    {
                        help += Calc(second, n, len+1, true);
                    }
                }
            }
            else
            {
                int limit = str[len]-'0';
                for (int n =0; n < limit; n++)
                {
                    if (n != first && n != second)
                    {
                        help += Calc(second, n, len + 1, true) ;
                    }
                }
                if (limit != first && limit != second )
                {
                    help += Calc(second, limit, len + 1, false);
                }
            }
            dp[first][second][len][all]= help;
        }
        return dp[first][second][len][all] ;
    }
}

ll Get (ll num)
{
    if (num < 0) return 0;
    stringstream ss ;
    ss << num;
    str = ss.str();
    memset(dp, -1, sizeof(dp));
    int first = str[0] - '0';
    ll res = 1;
    for ( int n = 1; n <= first ; n++)
    {
        res += Calc(n, n, 1, n != first);
    }
    for (int k = 2; k <= str.length() ; k++)
    {
        for ( int n = 1; n < 10; n++)
        {
            res += Calc (n, n, k, true) ;
        }
    }
    return res ;
}

int main ()
{
    ll a, b;
    cin >> a >> b;
    cout << Get(b) - Get(a - 1);
}

Compilation message (stderr)

numbers.cpp: In function 'll Calc(int, int, int, bool)':
numbers.cpp:11:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   11 |     if (len >= str.length())
      |         ~~~~^~~~~~~~~~~~~~~
numbers.cpp: In function 'll Get(ll)':
numbers.cpp:64:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   64 |     for (int k = 2; k <= str.length() ; k++)
      |                     ~~^~~~~~~~~~~~~~~

• Subtask 1: 25 / 25
• Subtask 2: 75 / 75