Given a number N which is prime. The task is to find all the numbers less than or equal to 10^6 whose minimum prime factor is N.
Input: N = 2 Output: 500000 Input: N = 3 Output: 166667
Approach: Use sieve of Eratosthenes to find the solution of the problem. Store all the prime numbers less than 10^6 . Form another sieve which will store the count of all the numbers whose minimum prime factor is the index of the sieve. Then display the count of the prime number N (i.e. sieve_count[n]+1), where n is the prime number .
Below is the implementation of above approach:
Count = 500000 Count = 166667
- Least prime factor of numbers till n
- Exactly n distinct prime factor numbers from a to b
- Count of subarrays whose products don't have any repeating prime factor
- Count all the numbers in a range with smallest factor as K
- Numbers with sum of digits equal to the sum of digits of its all prime factor
- Prime Factor
- Sum of all the prime numbers with the count of digits ≤ D
- Count of numbers below N whose sum of prime divisors is K
- Find count of Almost Prime numbers from 1 to N
- Minimum and Maximum prime numbers in an array
- N-th prime factor of a given number
- k-th prime factor of a given number
- Count common prime factors of two numbers
- Count numbers from range whose prime factors are only 2 and 3
- Numbers in range [L, R] such that the count of their divisors is both even and prime
If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to firstname.lastname@example.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.