Submission #248563

#	Time	Username	Problem	Language	Result	Execution time	Memory
248563		eohomegrownapps	Palindrome-Free Numbers (BOI13_numbers)	C++14	72.50 / 100	1 ms	384 KiB

numbers

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

string s;

ll dpv[20][10][10][2];

ll dp(int ind, int secondlast, int last, bool isSame){
	if (ind==s.size()){
		return 1;
	}
	if (secondlast!=-1&&dpv[ind][secondlast][last][isSame]!=-1){
		return dpv[ind][secondlast][last][isSame];
	}
	int upper = isSame ? s[ind]-'0' : 9;
	ll total = 0;
	for (int i = 0; i<=upper; i++){
		if (i==last || i==secondlast){continue;}
		total+=dp(ind+1,last,i,isSame&&i==(s[ind]-'0'));
	}
	if (secondlast!=-1){
		dpv[ind][secondlast][last][isSame]=total;
	}
	return total;
}

void initdp(){
	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<2; l++){
					dpv[i][j][k][l]=-1;
				}
			}
		}
	}
}

int main(){
	cin.tie(0);
	ios_base::sync_with_stdio(0);
	ll a,b;
	cin>>a>>b;
	a--;
	s=to_string(b);
	initdp();
	ll tot = dp(0,-1,-1,true);
	if (a>=0){
		s=to_string(a);
		initdp();
		tot-=dp(0,-1,-1,true);
	}
	cout<<tot<<'\n';
}

Compilation message (stderr)

numbers.cpp: In function 'll dp(int, int, int, bool)':
numbers.cpp:10:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  if (ind==s.size()){
      ~~~^~~~~~~~~~

• Subtask 1: 12.5 / 25
• Subtask 2: 60 / 75