71. Simplify Path
Medium
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Given an absolute path for a file (Unix-style), simplify it. Or in other words, convert it to the canonical path.
In a UNIX-style file system, a period . refers to the current directory. Furthermore, a double period .. moves the directory up a level. For more information, see: Absolute path vs relative path in Linux/Unix
Note that the returned canonical path must always begin with a slash /, and there must be only a single slash / between two directory names. The last directory name (if it exists) must not end with a trailing /. Also, the canonical path must be the shortest string representing the absolute path.
Example 1:
Input: "/home/" Output: "/home" Explanation: Note that there is no trailing slash after the last directory name.
Example 2:
Input: "/../" Output: "/" Explanation: Going one level up from the root directory is a no-op, as the root level is the highest level you can go.
Example 3:
Input: "/home//foo/" Output: "/home/foo" Explanation: In the canonical path, multiple consecutive slashes are replaced by a single one.
Example 4:
Input: "/a/./b/../../c/" Output: "/c"
Example 5:
Input: "/a/../../b/../c//.//" Output: "/c"
Example 6:
Input: "/a//b////c/d//././/.." Output: "/a/b/c" 搞清规则是很重要的，简而言之，遇到.代表当前层，忽略。..上一层，把已经入栈清除，剩下的文字都是正常的路径，但是开始要有/，中间的/只能有一个Python问题是，没有封装的类，对这个要自己实现，另外用Python函数实现对/的分割
class Solution(object):
def simplifyPath(self, path):
"""
:type path: str
:rtype: str
"""
# define stack
stack=list()
# split string
path=[p for p in path.split(‘/‘) if p]
for p in path:
if p == ‘.‘:
continue
elif p == ‘..‘:
if stack:
stack.pop()
else:
stack.append(p)
return ‘/‘+‘/‘.join(stack)
Solu=Solution()
path="/a/./b/../../c/"
print(Solu.simplifyPath(path))
BONUS:
1.有可能会出现多个/的情况，直接用split划分，会导致出现空字符串，解决方法是，加上判断语句。在循环过程直接加到stack里
2.
Python join() 方法用于将序列中的元素以指定的字符连接生成一个新的字符串。
语法
join()方法语法：
str.join(sequence)
原文地址：https://www.cnblogs.com/Marigolci/p/11616379.html