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"

.

Use stack to store each path name between "/". If ".." appears, pop the stack, if "." appears, do nothing, else push that path name into the stack. When this is done, send the names to a string, and add "/" between them.

public class Solution {
public String simplifyPath(String path) {
if (path == null || path.length() == 0) {
return path;
}

Stack<String> stack = new Stack<String>();
int i = 0;
while (i < path.length()) {
StringBuilder sb = new StringBuilder();
while (i < path.length() && path.charAt(i) != '/') {
sb.append(path.charAt(i));
i++;
}

String temp = sb.toString();
if (!temp.isEmpty()) {
if (temp.equals("..")) {
if (!stack.isEmpty()) {
stack.pop();
}
} else if (!temp.equals(".")) {
stack.push(temp);
}
}
i++;
}

StringBuilder res = new StringBuilder();
while (!stack.isEmpty()) {
res.insert(0, "/" + stack.pop());
}

if (res.length() == 0) {
return "/";
}
return res.toString();
}
}