Suppose we have a number n greater than 1, we have to find all of its prime factors and return them in sorted sequence. We can write out a number as a product of prime numbers, they are its prime factors. And the same prime factor may occur more than once.
So, if the input is like 42, then the output will be [2, 3, 7].
To solve this, we will follow these steps −
- res:= a new list
- while n mod 2 is same as 0, do
- insert 2 at the end of res
- n := quotient of n/2
- for i in range 3 to (square root of n), increase in step 2
- while n mod i is same as 0, do
- insert i at the end of res
- n := quotient of n/i
- while n mod i is same as 0, do
- if n > 2, then
- insert n at the end of res
- return res
Let us see the following implementation to get better understanding −
Example
class Solution: def solve(self, n): res=[] while n%2==0: res.append(2) n//=2 for i in range(3,int(n**.5)+1,2): while n%i==0: res.append(i) n//=i if n>2: res.append(n) return res ob = Solution() print(ob.solve(42))
Input
42
Output
[2, 3, 7]