C# 代码
public class Solution {
public int SumIndicesWithKSetBits(IList<int> nums, int k) {
return nums.Select((num, i) => BitCount(i) == k ? num : 0).Sum();
int BitCount(int x) {
int ans = 0;
while (x > 0){
x -= x & -x;
ans++;
}
return ans;
}
}
}