Package g1101_1200.s1175_prime_arrangements

Class Solution

  • All Implemented Interfaces:
    
public final class Solution

    1175 - Prime Arrangements\.

    Easy

    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

    Constraints:

    • 1 <= n <= 100

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description

    • Field Summary

      Fields 
      Modifier and Type Field Description

    • Constructor Summary

      Constructors 
      Constructor Description
      Solution()

    • Enum Constant Summary

      Enum Constants 
      Enum Constant Description

    • Method Summary

      Modifier and Type Method Description
      final Integer numPrimeArrangements(Integer n)

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait