1553Tight words

1553   Tight words

题目描述

Given is an alphabet {0, 1, ... , k}, 0 <= k <= 9 . We say that a word of length n over this alphabet is tight if any two neighbour digits in the word do not differ by more than 1.

输入格式:

Input is a sequence of lines, each line contains two integer numbers k and n, 1 <= n <= 100.

输出格式:

For each line of input, output the percentage of tight words of length n over the alphabet {0, 1, ... , k} with 5 fractional digits.

输入样例 复制
4 1
2 5
3 5
8 7
输出样例 复制
100.00000
40.74074
17.38281
0.10130

说明

5
6
通过提交
时空限制1000ms/128mb
题目来源
评测方式在线评测
题目类型
难        度