2220. Minimum Bit Flips to Convert Number
## 思路
檢查XOR之後的bit數
## Code
```python
class Solution:
def minBitFlips(self, start: int, goal: int) -> int:
res = 0
num = start ^ goal
while num:
res += 1
num &= num-1
return res
```
1318. Minimum Flips to Make a OR b Equal to c
## 思路
檢查a,b,c的bit
c=1