2020-05-13 No.71 简化路径

简化文件的绝对路径

示例1：
输入："/a/./b/../../c/"
输出："/c"
示例2:
输入："/a/../../b/../c//.//"
输出："/c"
示例3:
输入："/a//b////c/d//././/.."
输出："/a/b/c"

切换上级目录很巧妙

class Solution:
    def simplifyPath(self, path: str) -> str:
        tmp = path.split('/')
        res = []
        cnt = 0
        for i in range(len(tmp)-1, -1, -1):
            if tmp[i] == '' or tmp[i] == '.':
                continue
            elif tmp[i] == '..':
                cnt += 1
            elif cnt > 0:
                cnt -= 1
            else:
                res.append(tmp[i])
        return ('/' + '/'.join(res[::-1])) if res else '/'