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Tested Python solution for LeetCode 762 with 20 pytest cases. Generate a practice environment with lcpy.
lcpy gen -n 762 # by problem number
lcpy gen -s prime_number_of_set_bits_in_binary_representation # by problem name
left and right, return the count of numbers in the inclusive range [left, right] having a prime number of set bits in their binary representation.
Recall that the number of set bits an integer has is the number of 1’s present when written in binary.
21 written in binary is 10101, which has 3 set bits.Input: left = 6, right = 10
Output: 4
Explanation:
6 -> 110 (2 set bits, 2 is prime)
7 -> 111 (3 set bits, 3 is prime)
8 -> 1000 (1 set bit, 1 is not prime)
9 -> 1001 (2 set bits, 2 is prime)
10 -> 1010 (2 set bits, 2 is prime)
4 numbers have a prime number of set bits.
Input: left = 10, right = 15
Output: 5
Explanation:
10 -> 1010 (2 set bits, 2 is prime)
11 -> 1011 (3 set bits, 3 is prime)
12 -> 1100 (2 set bits, 2 is prime)
13 -> 1101 (3 set bits, 3 is prime)
14 -> 1110 (3 set bits, 3 is prime)
15 -> 1111 (4 set bits, 4 is not prime)
5 numbers have a prime number of set bits.
class Solution:
# Time: O((right - left) * log(right)) ~ O(w * 20) for w = right - left
# Space: O(1)
def count_prime_set_bits(self, left: int, right: int) -> int:
primes = {2, 3, 5, 7, 11, 13, 17, 19}
return sum(1 for n in range(left, right + 1) if n.bit_count() in primes)
| Time | Space |
|---|---|
| O((right - left) * log(right)) ~ O(w * 20) for w = right - left | O(1) |