leetcode 71. Simplify Path

题目
一开始想着用类似于split("\s+")这种的，发现没有，那就单个"/"划分吧，把空格的地方后期处理一下就行。因为StringBuilder的reverse是整个每个字符串都要翻转，所以要用到两个Stack

class Solution {
    public String simplifyPath(String path) {
        String[] str = path.split("/");
        Stack<String> stack = new Stack<>();
        for(int i=0;i<str.length;i++){
            if(str[i].length()==0 || str[i].equals(".")){
                continue;
            }else if(str[i].equals("..")){
                if(!stack.isEmpty()) stack.pop();
            }else{
                stack.push(str[i]);
            }
        }
        if(stack.isEmpty()) return "/";
        StringBuilder sb = new StringBuilder();
        Stack<String> stack1 = new Stack<>();
        while(!stack.isEmpty()){
            stack1.push(stack.pop());
        }
        while(!stack1.isEmpty()){
            sb.append("/");
            sb.append(stack1.pop());
        }
        return sb.toString();
    }
}