LeetCode 71. Simplify Path
一 题目
Given an absolute path for a file (Unix-style), simplify it. Or in other words, convert it to the canonical path.
In a UNIX-style file system, a period . refers to the current directory. Furthermore, a double period .. moves the directory up a level. For more information, see: Absolute path vs relative path in Linux/Unix
Note that the returned canonical path must always begin with a slash /, and there must be only a single slash / between two directory names. The last directory name (if it exists) must not end with a trailing /. Also, the canonical path must be the shorteststring representing the absolute path.
Example 1:
Input: "/home/" Output: "/home" Explanation: Note that there is no trailing slash after the last directory name.
Example 2:
Input: "/../" Output: "/" Explanation: Going one level up from the root directory is a no-op, as the root level is the highest level you can go.
Example 3:
Input: "/home//foo/" Output: "/home/foo" Explanation: In the canonical path, multiple consecutive slashes are replaced by a single one.
Example 4:
Input: "/a/./b/../../c/" Output: "/c"
Example 5:
Input: "/a/../../b/../c//.//" Output: "/c"
Example 6:
Input: "/a//bc/d//././/.." Output: "/a/b/c"
Accepted 167,020 Submissions 559,760
二 分析
medium 级别，题目要求把Unix操作系统的绝对路径变成简化路径。个人觉得有点实际意义，起码熟悉下路径，看脚本都好一些。
背景知识：熟悉的可以略过，“.” 当前层级，可以略过，“..”调到上一级。
路径都是“/”开头的。按要求简洁结束的“/”去掉。
回退的首先想到使用stack.利用出栈模拟“..”跳的上一级。
最后一点是输出结果的时候，注意下，栈是逆序输出的。
public static void main(String[] args) {
// TODO Auto-generated method stub
System.out.println( simplifyPath("/home/"));
System.out.println( simplifyPath("/../"));
System.out.println( simplifyPath("/home//foo/"));
System.out.println( simplifyPath("/a/./b/../../c/"));
System.out.println( simplifyPath("/a/../../b/../c//.//"));
System.out.println( simplifyPath("/a//bc/d//././/.."));
}
/**
* @author bohu83
* @param path
* @return
*/
public static String simplifyPath(String path) {
String[] strs= path.split("/");
Stack s = new Stack();
for(int i=0;iRuntime: 5 ms, faster than 65.62% of Java online submissions for Simplify Path.
Memory Usage: 36.9 MB, less than 100.00% of Java online submissions forSimplify Path.
时间复杂度O（N）
总的来说，相对容易些.不想别的medium那么难。要想再快就得看看怎么优化下。