leetcode: 71. Simplify Path

# 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".

# 思路：
# 1. split "/" 形成List, 同时剔除 "." 和 ""
# 2. 如果 ".." 就　pop 前面的
# 3. 反之则入队

class Solution():
    def simplifyPath(self, path):
        tokens, stack = [p for p in path.split("/") if p!="." and p!=""], []
        for t in tokens:
            if t == "..":
                if stack:
                    stack.pop()
            else:
                stack.append(t)
        return "/" + "/".join(stack)


if __name__ == "__main__":
    assert Solution().simplifyPath("/home//foo/") == '/home/foo'