Submission #284639

#	Time	Username	Problem	Language	Result	Execution time	Memory
284639		ChrisT	Palindrome-Free Numbers (BOI13_numbers)	C++17	100 / 100	1 ms	512 KiB

numbers

#include <bits/stdc++.h>
using namespace std;
const int MN = 1e3 + 5;
long long dp[2][20][10][10]; //dp[<=][digit][last digit][2nd last digit]
long long solve (long long x) {
	long long ret = 0; memset(dp,0,sizeof dp);
	for (int i = 0; i < min(100LL,x+1); i++) if (i < 10 || i/10 != i%10){
		++ret;
		dp[0][0][i/10][i%10] = 1;
		if (i <= x % 100) dp[1][0][i/10][i%10] = 1;
	}
	if (x<100) return ret;
	x /= 100;
	for (int i = 1; x; i++, x /= 10) {
		for (int take = 0; take < 10; take++) {
			for (int lst = 0; lst < 10; lst++) if (lst != take) {
				for (int bef = 0; bef < 10; bef++) if (lst != bef && bef != take) {
					dp[0][i][take][lst] += dp[0][i-1][lst][bef];
					if (take == x%10) dp[1][i][take][lst] += dp[1][i-1][lst][bef];
					else if (take < x%10) dp[1][i][take][lst] += dp[0][i-1][lst][bef];
				}
				if (!take) continue;
				if (x>=10) ret += dp[0][i][take][lst];
				else ret += dp[1][i][take][lst];
			}
		}
	}
	return ret;
}
int main () {
	long long a,b;
	scanf ("%lld %lld",&a,&b);
	printf ("%lld\n",solve(b) - solve(a-1));
	return 0;
}
 

Compilation message (stderr)

numbers.cpp: In function 'int main()':
numbers.cpp:32:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   32 |  scanf ("%lld %lld",&a,&b);
      |  ~~~~~~^~~~~~~~~~~~~~~~~~~

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