Submission #596919

#	Time	Username	Problem	Language	Result	Execution time	Memory
596919		Hanksburger	Palindrome-Free Numbers (BOI13_numbers)	C++17	100 / 100	1 ms	240 KiB

numbers

#include <bits/stdc++.h>
using namespace std;
#define ll long long
ll p[20];
ll f(ll n)
{
    if (n<=9)
        return n+1;
    stringstream ss;
    string s;
    ss << n;
    ss >> s;
    ll len=s.length();
    ll ans=10+81*(p[len-2]-1)/7+(s[0]-'1')*9*p[len-2]+(s[1]-'0'-(s[0]<s[1]))*p[len-2];
    if (s[0]==s[1])
        return ans;
    for (ll i=2; i<len; i++)
    {
        ans+=max(0, s[i]-'0'-(s[i-1]<s[i])-(s[i-2]<s[i]))*p[len-i-1];
        if (s[i-1]==s[i] || s[i-2]==s[i])
            return ans;
    }
    return ans+1;
}
int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    p[0]=1;
    for (ll i=1; i<20; i++)
        p[i]=p[i-1]*8;
    ll a, b;
    cin >> a >> b;
    cout << f(b)-f(a-1);
    return 0;
}

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