【LeetCode with Python】 71. Simplify Path

题目

原题页面:https://oj.leetcode.com/problems/simplify-path/
本文地址:http://leetcode.xnerv.wang/simplify-path/
题目类型:Stack, String
难度评价:Medium

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

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

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".

分析

用栈分析Linux路径,得出最后的结果。需要注意的就是Corner Cases了,如果是Windows用的相对较多的同学,很可能就不会注意到这些细节。但实际上很多涉及路径的win32 API也支持这种Corner Cases。


代码

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 "/"

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