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338.go
31 lines (26 loc) · 802 Bytes
/
338.go
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package p338
/**
Given a non negative integer number num. For every numbers i in the range 0 ≤ i ≤ num calculate the number of 1's in their binary representation and return them as an array.
Example:
For num = 5 you should return [0,1,1,2,1,2].
Follow up:
It is very easy to come up with a solution with run time O(n*sizeof(integer)). But can you do it in linear time O(n) /possibly in a single pass?
Space complexity should be O(n).
Can you do it like a boss? Do it without using any builtin function like __builtin_popcount in c++ or in any other language.
**/
func countBits(num int) []int {
num++
res := make([]int, num)
half := 1
for {
cnt := copy(res[half:], res[:half])
for i := 0; i < cnt; i++ {
res[half+i]++
}
if cnt < half {
break
}
half *= 2
}
return res
}