#2859
Sum of Values at Indices With K Set Bits
newbie · 125 · lc easy +13 · verified · 86.1% accepted · 318 likes · top 97%
Description
A 0-indexed integer array nums and an integer k are given.
Return the sum of all nums[i] whose index i has exactly k set bits in its binary representation.
Set bits are the 1s in the binary form of an integer. For example, 21 = 10101_2 has 3 set bits.
Example 1:
Input: nums = [5,10,1,5,2], k = 1
Output: 13
Explanation: The binary representation of the indices are:
0 = 0002
1 = 0012
2 = 0102
3 = 0112
4 = 1002
Indices 1, 2, and 4 have k = 1 set bits in their binary representation.
Hence, the answer is nums[1] + nums[2] + nums[4] = 13.
Example 2:
Input: nums = [4,3,2,1], k = 2
Output: 1
Explanation: The binary representation of the indices are:
0 = 002
1 = 012
2 = 102
3 = 112
Only index 3 has k = 2 set bits in its binary representation.
Hence, the answer is nums[3] = 1.
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