Simplify Path

题目

Given an absolute path for a file (Unix-style), simplify it.

For example,
path = "/home/", => "/home"
path = "/a/./b/../../c/", => "/c"

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".

方法

题目的要求是输出Unix下的最简路径，Unix文件的根文件夹为"/"，"."表示当前文件夹，".."表示上级文件夹。

使用Stack来进行处理。

    public String simplifyPath(String path) {
    	Stack<String> stack = new Stack<String>();
    	String str = "";
    	for (int i = 0; i < path.length(); i++) {
    		if (path.charAt(i) == '/') {
    			if (str.equals("..")) {
    				if (!stack.isEmpty()) {
    					stack.pop();
    				}
    			} else if (!str.equals(".") && !str.equals("")) {
    				stack.push(str);
    			}
    			str = "";
    		} else {
    			str += path.charAt(i);
    		}
    	}
    	if (str.equals("..")) {
			if (!stack.isEmpty()) {
				stack.pop();
			}
    	} else if (!str.equals(".") && !str.equals("")) {
    		stack.push(str);
    	}
    	
    	if (stack.isEmpty()) {
    		return "/";
    	}
    	
    	String re = "";
    	while (!stack.isEmpty()) {
    		re = "/" + stack.pop() + re;
    	}
    	return re;
    }