71. Simplify Path

public String simplifyPath1(String path) {
if(path == null || path.length() == 0) {
return "";
}
StringBuilder sb = new StringBuilder();
Stack<String> stack = new Stack<String>();
int i = 0;
while(i < path.length()) {
StringBuilder temp = new StringBuilder();
int index = i;
while(i < path.length() && path.charAt(i) != '/') {
temp.append(path.charAt(i));
i++;
}
if(index != i) {
String str = temp.toString();
if(str.equals("..")) {
if(!stack.isEmpty()) {
stack.pop();
}
} else if(!str.equals(".")) {
stack.push(str);
}
}
i++;
}
int size = stack.size();
for(int j = 0; j < size; j++) {
sb.insert(0,stack.pop());
sb.insert(0,"/");
}
return (sb.length() == 0)? "/":sb.toString();
}