Simplify Path

Author: mengli

SimplifyPath.java

@@ -0,0 +1,57 @@
+import java.util.LinkedList;
+import java.util.List;
+
+/**
+ * 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".
+ *
+ */
+
+public class SimplifyPath {
+	public String simplifyPath(String path) {
+		int length = path.length();
+		if (length == 0)
+			return path;
+		List<String> dicts = new LinkedList<String>();
+		int slow = 0;
+		int fast = 0;
+		while (true) {
+			while (slow < length && path.charAt(slow) == '/') {
+				slow++;
+			}
+			if (slow >= length)
+				break;
+			fast = slow;
+			while (fast < length && path.charAt(fast) != '/') {
+				fast++;
+			}
+			String s = path.substring(slow, fast);
+			if (s.equals("..")) {
+				if (!dicts.isEmpty()) {
+					dicts.remove(dicts.size() - 1);
+				}
+			} else if (!s.equals(".")) {
+				dicts.add(s);
+			}
+			slow = fast;
+		}
+		StringBuffer ret = new StringBuffer();
+		for (String s : dicts) {
+			ret.append('/');
+			ret.append(s);
+		}
+		return ret.length() == 0 ? "/" : ret.toString();
+	}
+}