CF258B.Little Elephant and Elections
普及+/提高
通过率:0%
时间限制:2.00s
内存限制:256MB
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题目描述
There have recently been elections in the zoo. Overall there were 7 main political parties: one of them is the Little Elephant Political Party, 6 other parties have less catchy names.
Political parties find their number in the ballot highly important. Overall there are m possible numbers: 1, 2, ..., m. Each of these 7 parties is going to be assigned in some way to exactly one number, at that, two distinct parties cannot receive the same number.
The Little Elephant Political Party members believe in the lucky digits 4 and 7. They want to evaluate their chances in the elections. For that, they need to find out, how many correct assignments are there, such that the number of lucky digits in the Little Elephant Political Party ballot number is strictly larger than the total number of lucky digits in the ballot numbers of 6 other parties.
Help the Little Elephant Political Party, calculate this number. As the answer can be rather large, print the remainder from dividing it by 1000000007 (109 + 7).
动物园最近举行了选举。总共有 7 个主要政党:其中之一是“小象政党”,其余 6 个政党的名称则没那么朗朗上口。
政党认为自己在选票上的编号极为重要。总共有 $ m $ 个可能的编号:$ 1,,2,,\dots,,m $。这 7 个政党中的每一个都将被恰好分配一个编号,且任意两个不同政党不能获得相同的编号。
“小象政党”的成员相信幸运数字 4 和 7。他们希望评估自己在选举中的胜算。为此,他们需要计算:有多少种合法的编号分配方案,使得“小象政党”所获编号中幸运数字(即数字 4 和 7)的个数严格大于其余 6 个政党所获编号中幸运数字的总数?
请帮助“小象政党”计算该数目。由于答案可能非常大,请输出其对 $ 1000000007 $(即 $ 10^9 + 7 $)取模的结果。
输入格式
A single line contains a single positive integer m (7 ≤ m ≤ 109) — the number of possible numbers in the ballot.
一行包含一个正整数 m(7≤m≤109)——选票中可能的数字个数。
输出格式
In a single line print a single integer — the answer to the problem modulo 1000000007 (109 + 7).
在一行中输出一个整数——该问题答案对 1000000007(109+7)取模的结果。
输入输出样例
输入#1
7
输出#1
0
输入#2
8
输出#2
1440
输入解题思路,AI测评打分。不知道怎么写?