Chtholly's request code force-897B
If a number is palindrome and length of its decimal representation without leading zeros is even, we call it a zcy number. A number is palindrome means when written in decimal representation, it contains no leading zeros and reads the same forwards and backwards. For example 12321 and 1221 are palindromes and 123 and 12451 are not. Moreover, 1221 is zcy number and 12321 is not.
Given integers k and p, calculate the sum of the k smallest zcy numbers and output this sum modulo p.
Unfortunately, Willem isn't good at solving this kind of problems, so he asks you for help!
The first line contains two integers k and p (1 ≤ k ≤ 105, 1 ≤ p ≤ 109).
Output single integer — answer to the problem.
2 100
33
5 30
15
In the first example, the smallest zcy number is 11, and the second smallest zcy number is 22.
In the second example, .
题解:怎么枚举偶数位的回文数?从小到大该怎么想?把一个数与它翻转后的数连接在一起,就构成了偶数位的回文数,比如12,翻转后21,连在一起1221。
1 // ConsoleApplication3.cpp: 定义控制台应用程序的入口点。 2 // 3 4 #include"stdafx.h" 5 #include<cstdio> 6 #include<cstring> 7 #include<iostream> 8 #include<algorithm> 9 using namespace std; 10 typedef long long ll; 11 12 ll cal(int m) { 13 ll ans = m, t = m; 14 while (t) { 15 ans = ans * 10 + t % 10; 16 t = t / 10; 17 } 18 return ans; 19 } 20 21 int main() 22 { 23 int k, p; 24 cin >> k >> p; 25 ll sum = 0; 26 for (int i = 1; i <= k; i++) sum = (sum + cal(i)) % p; 27 cout << sum << endl; 28 return 0; 29 }