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描述
You are given a string s, where every two consecutive vertical bars '|' are grouped into a pair. In other words, the 1st and 2nd '|' make a pair, the 3rd and 4th '|' make a pair, and so forth. Return the number of '*' in s, excluding the '*' between each pair of '|'. Note that each '|' will belong to exactly one pair.
Example 1:
Input: s = "l|*e*et|c**o|*de|"
Output: 2
Explanation: The considered characters are underlined: "l|*e*et|c**o|*de|".
The characters between the first and second '|' are excluded from the answer.
Also, the characters between the third and fourth '|' are excluded from the answer.
There are 2 asterisks considered. Therefore, we return 2.
Example 2:
Input: s = "iamprogrammer"
Output: 0
Explanation: In this example, there are no asterisks in s. Therefore, we return 0.
Example 3:
Input: s = "yo|uar|e**|b|e***au|tifu|l"
Output: 5
Explanation: The considered characters are underlined: "yo|uar|e**|b|e***au|tifu|l". There are 5 asterisks considered. Therefore, we return 5.
Note:
1 <= s.length <= 1000
s consists of lowercase English letters, vertical bars '|', and asterisks '*'.
s contains an even number of vertical bars '|'.
解析
根据题意，给定一个字符串 s ，其中每两个连续的竖线 '|' 中包含的字符串是合法的字符串。 换句话说，第一个和第二个 '|' 中的字符串是合法的，第三个和第四个 '|' 中的字符串是合法的，依此类推。返回 s 中不合法的字符串中的 '*' 的个数。
这道题其实很简单，只不过英文题目描述起来不那么容易理解，我们只需要换个思路，不去被这个 “｜” 所束缚，反正目标是找不合法字符串中的星号数量，我们只需要对 s 按照 “｜” 进行分割成字符串列表 L ，此时偶数索引的字符串就是题目中说的不合法字符串，然后只需要找到偶数索引的字符串，将他们里面的星号数量进行计数然后加到 result 中即可。
时间复杂度为 O(N) ，空间复杂度为 O(N) 。
解答
class Solution(object):
def countAsterisks(self, s):
"""
:type s: str
:rtype: int
"""
result = 0
L = s.split('|')
N = len(L)
for i in range(0,N,2):
result += L[i].count('*')
return result
运行结果
69 / 69 test cases passed.
Status: Accepted
Runtime: 41 ms
Memory Usage: 13.6 MB
原题链接
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