Submission #283086

#	Time	Username	Problem	Language	Result	Execution time	Memory
283086		theStaticMind	Palindrome-Free Numbers (BOI13_numbers)	C++14	100 / 100	1 ms	384 KiB

numbers

#include<bits/stdc++.h>
#define pb push_back
#define ii pair<int,int>
#define all(x) (x).begin(),(x).end()
#define sz(x) ((int)(x).size())
#define INF 100000000000000000
#define modulo 1000000007
#define mod 998244353
#define int long long int
using namespace std;

int count(int n, int s){
	int ret = 1;
	for(int i = 0; i < n; i++){
		ret *= max(s--, 8ll);
	}
	return ret;
}

int solve(string s){
	int n = sz(s);
	int cnt = 1;
	cnt += max(0ll, 0ll+s[0] - '1') * count(n - 1, 9);
	for(int i = 1; i < sz(s); i++) cnt += 9ll * count(n - i - 1, 9);
	for(int i = 1; i < sz(s); i++){
		cnt += max(0ll, 0ll+s[i] - '0' - (s[i-1] < s[i] ? 1 : 0) - (i>1 && s[i - 2] < s[i] ? 1 : 0)) * count(n - i - 1, 8);
		if(s[i] == s[i - 1] || (i > 1 && s[i] == s[i - 2])){
			cnt--;
			break;
		}
	}
	return cnt;
}

int32_t main(){
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);

	int a, b;
	cin >> a >> b;


	cout << (b ? solve(to_string(b)) : 0) - (a > 1 ? solve(to_string(a - 1)) : a - 1);
}

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