Leetcode1175. Prime Arrangements
2023-01-02 16:13 作者:您是打尖儿还是住店呢 | 我要投稿
Return the number of permutations of 1 to n so that prime numbers are at prime indices (1-indexed.)
(Recall that an integer is prime if and only if it is greater than 1, and cannot be written as a product of two positive integers both smaller than it.)
Since the answer may be large, return the answer modulo 10^9 + 7.
Example 1:
Input: n = 5
Output: 12
Explanation: For example [1,2,5,4,3] is a valid permutation, but [5,2,3,4,1] is not because the prime number 5 is at index 1.
Example 2:
Input: n = 100
Output: 682289015
写个for循环不会溢出，单独写个函数，求阶乘的，就会溢出，呵呵，不过在本机自己电脑上是可以运行的。
Constraints:
1 <= n <= 100
Runtime0 ms
Beats
100%
Memory38.9 MB
Beats
94.38%
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