Sum of Values at Indices With K Set Bits — LeetCode 2859 Python Solution

The problem

You are given a 0-indexed integer array nums and an integer k. Return an integer that denotes the sum of elements in nums whose corresponding indices have exactly k set bits in their binary representation.

Example

Input

nums = [5,10,1,5,2], k = 1

Output

13

Explanation

The binary representation of the indices are:

Python solution

class Solution:
    def sumIndicesWithKSetBits(self, nums: List[int], k: int) -> int:
        return sum(x for i, x in enumerate(nums) if i.bit_count() == k)

Complexity

Pattern: Bit Manipulation

Use XOR, masks and the low-bit trick to replace whole data structures with an integer. LeetCode 2859. Sum of Values at Indices With K Set Bits 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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