Submission #462607

#	Time	Username	Problem	Language	Result	Execution time	Memory
462607		JovanB	Palindrome-Free Numbers (BOI13_numbers)	C++17	100 / 100	4 ms	436 KiB

numbers

#include <bits/stdc++.h>
using namespace std;
 
typedef long long ll;
 
ll dp[3][25][15][15];

string tostr(ll n){
    string s = "";
    while(n){
        s += '0' + (n%10);
        n /= 10;
    }
    reverse(s.begin(), s.end());
    return s;
}
 
ll solve(ll n){
    for(int i=0; i<=20; i++){
        for(int j=0; j<=10; j++){
            for(int k=0; k<=10; k++){
                for(int l=0; l<=10; l++){
                    dp[0][i][j][k] = dp[1][i][j][k] = dp[2][i][j][k] = 0;
                }
            }
        }
    }
    dp[0][0][0][0] = 1;
    string s = tostr(n);
    int len = s.size();
    for(int i=0; i<len; i++){
        for(int j=0; j<=10; j++){
            for(int k=0; k<=10; k++){
                for(int l=1; l<=10; l++){
                    if(l == j || l == k) continue;
                    if(!i && l == 1) continue;
                    dp[1][i+1][k][l] += dp[1][i][j][k];
                    if(l-1 < s[i]-'0'){
                        dp[1][i+1][k][l] += dp[0][i][j][k];
                    }
                    if(l-1 == s[i]-'0'){
                        dp[0][i+1][k][l] += dp[0][i][j][k];
                    }
                }
            }
        }
    }
    ll res = 0;
    for(int i=0; i<=10; i++){
        for(int j=0; j<=10; j++){
            res += dp[0][len][i][j] + dp[1][len][i][j];
        }
    }
    return res;
}
 
ll resi(ll n){
    ll k = 0;
    ll res = 0;
    while(k < n){
        res += solve(k);
        k = 10*k+9;
    }
    res += solve(n);
    return res;
}
 
int main(){
    ios_base::sync_with_stdio(false);
 
    ll a, b;
    cin >> a >> b;
    cout << resi(b) - resi(a-1);
    return 0;
}

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