Submission #230477

#	Time	Username	Problem	Language	Result	Execution time	Memory
230477		alishahali1382	Palindrome-Free Numbers (BOI13_numbers)	C++14	100 / 100	6 ms	400 KiB

numbers

#include <bits/stdc++.h>
#pragma GCC optimize ("O2")
#pragma GCC optimize ("unroll-loops")
//#pragma GCC optimize("no-stack-protector,fast-math")

using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<pii, int> piii;
typedef pair<ll, ll> pll;
#define debug(x) cerr<<#x<<'='<<(x)<<endl;
#define debugp(x) cerr<<#x<<"= {"<<(x.first)<<", "<<(x.second)<<"}"<<endl;
#define debug2(x, y) cerr<<"{"<<#x<<", "<<#y<<"} = {"<<(x)<<", "<<(y)<<"}"<<endl;
#define debugv(v) {cerr<<#v<<" : ";for (auto x:v) cerr<<x<<' ';cerr<<endl;}
#define all(x) x.begin(), x.end()
#define pb push_back
#define kill(x) return cout<<x<<'\n', 0;

const ld eps=1e-7;
const int inf=1000000010;
const ll INF=10000000000000010LL;
const int mod=1000000007;
const int MAXN=100010, LOG=20;

ll n, m, k, u, v, x, y, t, a, b, ans;
ll tav10[MAXN], tav8[MAXN], dp[LOG];

int get_len(ll x){
	if (!x) return 0;
	return 1+get_len(x/10);
}

ll Solve(ll num){
	ll res=0, len=get_len(num);
	for (int i=0; i<len; i++) res+=dp[i];
	vector<int> vec={-1, -1};
	for (int i=len-1; ~i; i--){
		ll dig=(num/tav10[i])%10;
		for (int j=(i==len-1); j<dig; j++) if (j!=vec.back() && j!=vec[vec.size()-2]){
			if (i==len-1){
				if (!i) res++;
				else res+=9*tav8[i-1];
			}
			else{
				res+=tav8[i];
			}
		}
		if (vec.back()==dig || vec[vec.size()-2]==dig) return res;
		vec.pb(dig);
	}
	return res;
}

int main(){
	ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
	//freopen("input.txt", "r", stdin);
	//freopen("output.txt", "w", stdout);
	tav8[0]=tav10[0]=1;
	for (int i=1; i<LOG; i++){
		tav8[i]=tav8[i-1]*8ll;
		tav10[i]=tav10[i-1]*10ll;
	}
	dp[1]=9ll;
	dp[2]=81ll;
	for (int i=3; i<LOG; i++) dp[i]=dp[i-1]*8ll;
	
	cin>>a>>b;
	cout<<Solve(b+1)-Solve(a)+(a==0)<<'\n';
	
	return 0;
}

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