제출 #857001

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
857001		MrMody	Palindrome-Free Numbers (BOI13_numbers)	C++17	100 / 100	1 ms	600 KiB

numbers

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define el "\n"
#define fio ios_base::sync_with_stdio(0),cin.tie(0),cout.tie(0);

long long a,b;
long long dp[22][2][10][10][2][2];
int d[22],cnt;
 
int get_digits(long long n) {
    cnt=0;
    while(n) d[cnt++]=n%10,n/=10;
    reverse(d,d+cnt);
    return 0;
}
 
long long rec(int pos, int f, int before_last, int last, int has_before_last, int has_last) {
    if(pos == cnt)
        return has_last;
    auto &ret = dp[pos][f][before_last][last][has_before_last][has_last];
    if(ret != -1)
        return ret;
    ret = 0;
    int i;
    for(i=0;i<10;i++) {
        if(f || i<=d[pos]){
            if(!has_last || last!=i){
                if(!has_before_last || before_last!=i) {
                    ret += rec(pos+1,f|(i<d[pos]),last,i,has_last,has_last|(i>0));
                }
            }
        }
    }
    return ret;
}
 
long long f(long long n) {
    get_digits(n);
    memset(dp,-1,sizeof(dp));
    return 1 + rec(0,0,0,0,0,0);
}

int main() {
    fio
    cin >> a >> b;
    cout << f(b) - (a > 0 ? f(a-1):0);
    return 0;
}

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