Prime Number of Set Bits in Binary Representation — LeetCode 762 Python Solution

The problem

Given two integers 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.

Example

Input

left = 6, right = 10

Output

4

Explanation

6 -> 110 (2 set bits, 2 is prime)

Python solution

class Solution:
    def countPrimeSetBits(self, left: int, right: int) -> int:
        primes = {2, 3, 5, 7, 11, 13, 17, 19}
        return sum(i.bit_count() in primes for i in range(left, right + 1))

Complexity

Pattern: Bit Manipulation

Use XOR, masks and the low-bit trick to replace whole data structures with an integer. LeetCode 762. Prime Number of Set Bits in Binary Representation is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Bit Manipulation.

The bit manipulation guide has the Python template for the pattern and the 194 LeetCode problems that use it.

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