Given an integer N. The task is to find the number of divisors of all the numbers in the range [1, N].
Input: N = 5
Output: 1 2 2 3 2
divisors(1) = 1
divisors(2) = 1 and 2
divisors(3) = 1 and 3
divisors(4) = 1, 2 and 4
divisors(5) = 1 and 5
Input: N = 10
Output: 1 2 2 3 2 4 2 4 3 4
Approach: Create an array arr of the size (N + 1) where arr[i] stores the number of divisors of i. Now for every j from the range [1, N], increment all the elements which are divisible by j.
For example, if j = 3 then update arr, arr, arr, …
Below is the implementation of the above approach:
1 2 2 3 2 4 2 4 3 4
- Program to find count of numbers having odd number of divisors in given range
- Find numbers with K odd divisors in a given range
- Find numbers with n-divisors in a given range
- Find the number of integers x in range (1,N) for which x and x+1 have same number of divisors
- Sum of all prime divisors of all the numbers in range L-R
- Sum of numbers in a range [L, R] whose count of divisors is prime
- Numbers in range [L, R] such that the count of their divisors is both even and prime
- Find sum of inverse of the divisors when sum of divisors and the number is given
- Find sum of divisors of all the divisors of a natural number
- Find kth smallest number in range [1, n] when all the odd numbers are deleted
- Querying maximum number of divisors that a number in a given range has
- Count elements in the given range which have maximum number of divisors
- Find two numbers whose divisors are given in a random order
- Count the numbers < N which have equal number of divisors as K
- Find the sum of the number of divisors
If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to email@example.com. 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.