2595. Smallest Value After Replacing With Sum of Prime Factors

Medium
Math
Simulation
Number Theory

Description

You are given a positive integer n.

Continuously replace n with the sum of its prime factors.

  • Note that if a prime factor divides n multiple times, it should be included in the sum as many times as it divides n.

Return the smallest value n will take on.

 

Example 1:

Input: n = 15
Output: 5
Explanation: Initially, n = 15.
15 = 3 * 5, so replace n with 3 + 5 = 8.
8 = 2 * 2 * 2, so replace n with 2 + 2 + 2 = 6.
6 = 2 * 3, so replace n with 2 + 3 = 5.
5 is the smallest value n will take on.

Example 2:

Input: n = 3
Output: 3
Explanation: Initially, n = 3.
3 is the smallest value n will take on.

 

Constraints:

  • 2 <= n <= 105

Hints

Hint 1
Every time you replace n, it will become smaller until it is a prime number, where it will keep the same value each time you replace it.
Hint 2
n decreases logarithmically, allowing you to simulate the process.
Hint 3
To find the prime factors, iterate through all numbers less than n from least to greatest and find the maximum number of times each number divides n.

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