Submission #170312

#	Time	Username	Problem	Language	Result	Execution time	Memory
170312		ngmh	Palindrome-Free Numbers (BOI13_numbers)	C++11	100 / 100	3 ms	632 KiB

numbers

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

long long a, b, dp[20][11][11][3][3];
vector<long long> number;

long long derp(long long idx, long long prev1, long long prev2, long long same, long long allzero){
	if(idx == number.size()) dp[idx][prev1][prev2][same][allzero] = 1;
	if(dp[idx][prev1][prev2][same][allzero] != -1) return dp[idx][prev1][prev2][same][allzero];
	long long sum = 0, limit;
	if((!allzero && same) || (allzero && idx == 0)) limit = number[idx];
	else limit = 9;
	for(int i = 0; i <= limit; i++){
		if(allzero){
			if(i == 0) sum += derp(idx+1, 10, 10, 1, 1);
			else sum += derp(idx+1, i, 10, (idx == 0 && i == limit), 0);
		} else if(i != prev1 && i != prev2){
			if(same && i == number[idx]) sum += derp(idx+1, i, prev1, 1, 0);
			else sum += derp(idx+1, i, prev1, 0, 0);
		}
	}
	return dp[idx][prev1][prev2][same][allzero] = sum;
}

long long solve(long long num){
	if(num < 0) return 0;
	number.clear();
	while(num > 0){ number.push_back(num%10); num /= 10; }
	reverse(number.begin(), number.end());
	memset(dp, -1, sizeof(dp));
	return derp(0, 10, 10, 1, 1);
}

int main(){
	cin >> a >> b;
	cout << solve(b)-solve(a-1);
}

Compilation message (stderr)

numbers.cpp: In function 'long long int derp(long long int, long long int, long long int, long long int, long long int)':
numbers.cpp:8:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  if(idx == number.size()) dp[idx][prev1][prev2][same][allzero] = 1;
     ~~~~^~~~~~~~~~~~~~~~

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