add solution of problem 71: simplify path

Author: ppulse

SimplifyPath71/README.md

@@ -0,0 +1,5 @@
+Given an absolute path for a file (Unix-style), simplify it.
+
+For example,
+**path** = "/home/", => "/home"
+**path** = "/a/./b/../../c/", => "/c"

SimplifyPath71/Solution.java

@@ -0,0 +1,32 @@
+public class Solution {
+    public String simplifyPath(String path) {
+        if (path == null)
+            return "/";
+        
+        Stack<String> stack = new Stack<String>();
+        stack.push("/");
+        
+        String[] pathArray = path.split("/");
+        
+        for (int i = 0; i < pathArray.length; i++) {
+            if (pathArray[i].equals(".") || pathArray[i].equals("")) {
+                //do nothing
+            } else if (pathArray[i].equals("..")) {
+                if (!stack.peek().equals("/"))
+                    stack.pop();
+            } else {
+                stack.push(pathArray[i]);
+            }
+        }
+        
+        StringBuilder sb = new StringBuilder();
+        for (String s : stack) {
+        	sb.append(s);
+        	if (!s.equals("/"))
+        		sb.append("/");
+        }
+        
+        String result = sb.toString();
+        return result.length() > 1 ? result.substring(0, result.length() - 1) : result;
+    }
+}