共计 1111 个字符，预计需要花费 3 分钟才能阅读完成。
Problem
Given an absolute path for a file (Unix-style), simplify it.
For example,
path = “/home/”, => “/home”
path = “/a/./b/../../c/”, => “/c”
path = “/a/../../b/../c//.//”, => “/c” //here: b is cancelled out, a is cancelled out
path = “/a//b////c/d//././/..”, => “/a/b/c” //here d is cancelled out
In a UNIX-style file system, a period (‘.’) refers to the current directory, so it can be ignored in a simplified path. Additionally, a double period (“..”) moves up a directory, so it cancels out whatever the last directory was. For more information, look here: https://en.wikipedia.org/wiki…
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”.
Solution
class Solution {
public String simplifyPath(String path) {
Deque<String> stack = new ArrayDeque<>();
Set<String> ignore = new HashSet<>(Arrays.asList(“”, “.”, “..”));
for (String dir: path.split(“/”)) {
if (!stack.isEmpty() && dir.equals(“..”)) stack.pop();
if (!ignore.contains(dir)) stack.push(dir);
}
String res = “”;
while (!stack.isEmpty()) {
res = “/”+stack.pop()+res;
}
if (res.equals(“”)) return “/”;
return res;
}
}
