Leetcode-71. Simplify Path

前言：为了后续的实习面试，开始疯狂刷题，非常欢迎志同道合的朋友一起交流。因为时间比较紧张，目前的规划是先过一遍，写出能想到的最优算法，第二遍再考虑最优或者较优的方法。如有错误欢迎指正。博主首发CSDN，mcf171专栏。

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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".

这个题目想了下，用堆来解决，用正则表达式分割。不过貌似效率不咋的 Your runtime beats 9.13% of java submissions.

import java.util.regex.Pattern;
public class Solution {
    public String simplifyPath(String path) {
        Stack stack = new Stack();
        stack.push("/");
        StringBuffer sb = new StringBuffer("");
        String[] results = Pattern.compile("/+").split(path);
        for(String item : results){
            if(!item.equals("")){
                if(item.equals(".")) continue;
                if(item.equals("..")){
                    if(!(stack.peek().equals("/"))) stack.pop();
                }else{ stack.push(item);}
            }
        }

        while(!stack.empty()){
            sb.insert(0,stack.pop());
            sb.insert(0,"/");
        }
        sb.delete(0,2);
        if(sb.length() == 0) sb.append("/");
        return sb.toString();

    }
}