- LeetCode(172) Factorial Trailing
- LeetCode 172 [Factorial Trailing
- leetcode:172. Factorial Trailing
- [String]172. Factorial Trailing
- LeetCode 172. Factorial Trailing
- Leetcode 172. Factorial Trailing
- LeetCode 172. Factorial Trailing
- Leetcode.172.Factorial Trailing
- Leetcode 172. Factorial Trailing
- 172. Factorial Trailing Zeroes
原题
设计一个算法，计算出n阶乘中尾部零的个数
样例
11! = 39916800，因此应该返回 2
解题思路
- 数学问题，写成前几项找规律
5!, 包含1*5, 1个5 => 1个0
10!, 包含1*5,2*5, 2个5 => 2个0
15!, 包含1*5,2*5,3*5, 3个5 => 3个0
20!, 包含1*5,2*5,3*5,4*5, 4个5 => 4个0
25!, 包含1*5,2*5,3*5,4*5,5*5, 5个5 => 5个0
...
- 所以本题就转化为，找1到n中包含几个5
完整代码
class Solution(object):
def trailingZeroes(self, n):
"""
:type n: int
:rtype: int
"""
if not n:
return 0
res = 0
while n > 0:
res += n / 5
n /= 5
return res
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