【LeetCode with Python】 Simplify Path

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原题页面： https://oj.leetcode.com/problems/simplify-path/
题目类型：
难度评价：★
本文地址： http://blog.youkuaiyun.com/nerv3x3/article/details/39453399

Given an absolute path for a file (Unix-style), simplify it.

For example,
path = "/home/", => "/home"
path = "/a/./b/../../c/", => "/c"

click to show corner cases.

Corner Cases:

• Did you consider the case where path = "/../"?
  In this case, you should return "/".
• Another corner case is the path might contain multiple slashes '/' together, such as"/home//foo/".
  In this case, you should ignore redundant slashes and return "/home/foo".

class Solution:
    # @param path, a string
    # @return a string
    def simplifyPath(self, path):
        stack = [ ]
        toks = path.split("/")
        stack.append(toks[0])
        toks = toks[1:]
        for tok in toks:
            if tok in ("", "."):
                continue
            elif ".." ==  tok:
                if len(stack) > 0 and "" != stack[len(stack) - 1]:   # root / should not be poped to distinguish abs path and rel path
                    stack.pop()
                #else:
                #    return ""         # /home/../../..
            else:
                stack.append(tok)
        len_stack = len(stack)
        if len_stack >1:
            return "/".join(stack) if "" == stack[0] else "/" + "/".join(stack)
        elif (1 == len_stack and "" == stack[0]) or 0 == len_stack:
            return "/"