2028. Find Missing Observations
## 思路
先计算n个rolls的总和
如果不在全丢1或丢6的范围内 就回传[]
除上n, 让所有骰子全丢a
剩下的余数分配到b个骰子
## Code
```python
class Solution:
def missingRolls(self, rolls: List[int], mean: int, n: int) -> List[int]:
m = len(rolls)
total = (m+n) * mean - sum(rolls)
if total < n * 1 or total > n * 6:
return []
a, b = divmod(total, n)
return [a+1] * b + [a] * (n-b)
```