[Leetcode] 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".

 

Solution:

考察Java String的split function。

 

1. 先用/来split string
2. 然后看每一小段，若是”.”或者是“”（说明两个/连着），不入栈；若是”..”，pop；若是正常，push.

 

public class Solution {
    public String simplifyPath(String path) {
        if(path==null||path.length()==0)
            return "";
        if(path.equals("/"))
            return "/";
        String[] tokens=path.split("/");
        Stack<String> stack=new Stack<String>();
        
        for(int i=0;i<tokens.length;++i){
            if(tokens[i].equals("..")){
                if(!stack.empty())
                    stack.pop();
                else
                    continue;
            }else if(tokens[i].equals(".")||tokens[i].length()==0){
                continue;
            }else{
                stack.push(tokens[i]);
            }
        }
        
        Stack<String> stack2=new Stack<String>();
        String result=new String("");
        
        if(stack.empty())
            return "/";
        
        while(!stack.empty())
            stack2.push(stack.pop());
        while(!stack2.empty()){
            result+="/";
            result+=stack2.pop();
        }
        return result;   
    }
}