```
Given a non-negative integer num, return the number of steps to reduce it to zero. If the current number is even, you have to divide it by 2, otherwise, you have to subtract 1 from it.
Example 1:
Input: num = 14
Output: 6
Explanation:
Step 1) 14 is even; divide by 2 and obtain 7.
Step 2) 7 is odd; subtract 1 and obtain 6.
Step 3) 6 is even; divide by 2 and obtain 3.
Step 4) 3 is odd; subtract 1 and obtain 2.
Step 5) 2 is even; divide by 2 and obtain 1.
Step 6) 1 is odd; subtract 1 and obtain 0.
Example 2:
Input: num = 8
Output: 4
Explanation:
Step 1) 8 is even; divide by 2 and obtain 4.
Step 2) 4 is even; divide by 2 and obtain 2.
Step 3) 2 is even; divide by 2 and obtain 1.
Step 4) 1 is odd; subtract 1 and obtain 0.
Example 3:
Input: num = 123
Output: 12
```

解法一：递归

```
class Solution {
public:
int numberOfSteps (int num) {
return (num == 0)? 0:((num % 2 == 0) ? (numberOfSteps(num>>1) + 1):(numberOfSteps(num - 1) + 1));
}
};
```

解法二：

```
class Solution {
public:
int numberOfSteps (int num) {
int count = 0;
while(num != 0)
{
if(num % 2 == 0)
num >>= 1;
else
num -= 1;
count++;
}
return count;
}
};
```