Submission #741986

#	Time	Username	Problem	Language	Result	Execution time	Memory
741986		irmuun	Palindrome-Free Numbers (BOI13_numbers)	C++17	100 / 100	10 ms	212 KiB

numbers

#include<bits/stdc++.h>

using namespace std;

#define pb push_back
#define ll long long
#define ff first
#define ss second
#define all(s) s.begin(),s.end()

ll cnt[20],c8[20];

ll check(ll n){
    string s=to_string(n);
    for(ll i=1;i<s.size();i++){
        if(s[i]==s[i-1]){
            return 0;
        }
    }
    for(ll i=2;i<s.size();i++){
        if(s[i]==s[i-2]){
            return 0;
        }
    }
    return 1;
}

ll pal(ll n){
    if(n==0){
        return 0;
    }
    string s=to_string(n);
    ll sz=s.size();
    ll res=0;
    for(ll i=1;i<sz;i++){
        res+=cnt[i]*9;
    }
    //cout<<res<<"\n";
    for(ll i=0;i<sz;i++){
        for(ll j=(i==0?1:0);j<s[i]-48;j++){
            //cout<<"str "<<s.substr(0,i)<<char(j+48)<<"\n";
            if((i>0&&char(j+48)==s[i-1])||(i>1&&char(j+48)==s[i-2])){
                continue;
            }
            if(i==0){
                //cout<<cnt[sz-i]<<' ';
                res+=cnt[sz-i];
            }
            else{
                //cout<<c8[sz-i-1]<<' ';
                res+=c8[sz-i-1];
            }
            //cout<<"\n";
        }
        if((i>0&&s[i]==s[i-1])||(i>1&&s[i]==s[i-2])){
            break;
        }
    }
    //cout<<check(n);
    //cout<<"\n";
    return res+check(n);
}

int main(){
    ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
    cnt[0]=1;
    cnt[1]=1;
    cnt[2]=9;
    c8[0]=1;
    c8[1]=8;
    c8[2]=64;
    for(ll i=3;i<=18;i++){
        cnt[i]=cnt[i-1]*8;
        c8[i]=c8[i-1]*8;
    }
    ll a,b;
    cin>>a>>b;
    if(b-a<=100000){
        ll ans=0;
        for(ll i=a;i<=b;i++){
            ans+=check(i);
        }
        cout<<ans;
        return 0;
    }
    cout<<pal(b)-pal(a-1);
}

Compilation message (stderr)

numbers.cpp: In function 'long long int check(long long int)':
numbers.cpp:15:17: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   15 |     for(ll i=1;i<s.size();i++){
      |                ~^~~~~~~~~
numbers.cpp:20:17: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   20 |     for(ll i=2;i<s.size();i++){
      |                ~^~~~~~~~~

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