Given a non negative integer numbernum. For every numbersiin the range0 ≤ i ≤ numcalculate the number of 1's in their binary representation and return them as an array.
Example:
Fornum = 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.
Credits:
Special thanks to@ syedeefor adding this problem and creating all test cases.
class Solution {
public:
vector<int> countBits\(int num\) {
vector<int> result\(num+1\);
result\[0\]=0;
if \(num==0\){
return result;
}
int mark=2;
result\[1\]=1;
for \(int i=2;i<=num;i++\){
if\(i<=\(2\*mark-1\)\){
result\[i\]=result\[i-mark\]+1;
}
if\(i==\(2\*mark-1\)\){
mark=2\*mark;
}
}
return result;
}
};