refactor 606

Author: fishercoder1534

src/main/java/com/fishercoder/solutions/_606.java

@@ -39,23 +39,56 @@
  */
 public class _606 {
 
-    public String tree2str(TreeNode t) {
-        if (t == null) {
-            return "";
+    public static class Solution1 {
+        public String tree2str(TreeNode t) {
+            if (t == null) {
+                return "";
+            }
+            String result = "" + t.val;
+            String left = tree2str(t.left);
+            String right = tree2str(t.right);
+            if (left.equals("") && right.equals("")) {
+                return result;
+            }
+            if (left.equals("")) {
+                return result + "()(" + right + ")";
+            }
+            if (right.equals("")) {
+                return result + "(" + left + ")";
+            }
+            return result + "(" + left + ")(" + right + ")";
         }
-        String result = "" + t.val;
-        String left = tree2str(t.left);
-        String right = tree2str(t.right);
-        if (left.equals("") && right.equals("")) {
-            return result;
-        }
-        if (left.equals("")) {
-            return result + "()(" + right + ")";
+    }
+
+    public static class Solution2 {
+        public String tree2str(TreeNode t) {
+            if (t == null) {
+                return "";
+            }
+            StringBuilder sb = new StringBuilder();
+            preorder(t, sb);
+            return sb.toString();
         }
-        if (right.equals("")) {
-            return result + "(" + left + ")";
+
+        private void preorder(TreeNode root, StringBuilder sb) {
+            if (root == null) {
+                return;
+            }
+            sb.append(root.val);
+            if (root.left != null) {
+                sb.append("(");
+                preorder(root.left, sb);
+                sb.append(")");
+            }
+            if (root.right != null) {
+                if (root.left == null) {
+                    sb.append("()");
+                }
+                sb.append("(");
+                preorder(root.right, sb);
+                sb.append(")");
+            }
         }
-        return result + "(" + left + ")(" + right + ")";
     }
 
 }

src/test/java/com/fishercoder/_606Test.java

@@ -1,50 +1,47 @@
 package com.fishercoder;
 
 import com.fishercoder.common.classes.TreeNode;
+import com.fishercoder.common.utils.TreeUtils;
 import com.fishercoder.solutions._606;
 import org.junit.BeforeClass;
 import org.junit.Test;
 
+import java.util.Arrays;
+
 import static org.junit.Assert.assertEquals;
 
 /**
  * Created by stevesun on 6/4/17.
  */
 public class _606Test {
-    private static _606 test;
+    private static _606.Solution1 solution1;
+    private static _606.Solution2 solution2;
     private static TreeNode treeNode;
 
     @BeforeClass
     public static void setup() {
-        test = new _606();
+        solution1 = new _606.Solution1();
+        solution2 = new _606.Solution2();
     }
 
     @Test
     public void test1() {
-        treeNode = new TreeNode(1);
-        treeNode.left = new TreeNode(2);
-        treeNode.right = new TreeNode(3);
-        treeNode.left.left = new TreeNode(4);
-        System.out.println("Test1");
-        assertEquals("1(2(4))(3)", test.tree2str(treeNode));
+        treeNode = TreeUtils.constructBinaryTree(Arrays.asList(1, 2, 3, 4));
+        assertEquals("1(2(4))(3)", solution1.tree2str(treeNode));
+        assertEquals("1(2(4))(3)", solution2.tree2str(treeNode));
     }
 
     @Test
     public void test2() {
-        treeNode = new TreeNode(1);
-        treeNode.left = new TreeNode(2);
-        treeNode.right = new TreeNode(3);
-        treeNode.left.right = new TreeNode(4);
-        System.out.println("Test2");
-        assertEquals("1(2()(4))(3)", test.tree2str(treeNode));
+        treeNode = TreeUtils.constructBinaryTree(Arrays.asList(1, 2, 3, null, 4));
+        assertEquals("1(2()(4))(3)", solution1.tree2str(treeNode));
+        assertEquals("1(2()(4))(3)", solution2.tree2str(treeNode));
     }
 
     @Test
     public void test3() {
-        treeNode = new TreeNode(1);
-        treeNode.right = new TreeNode(2);
-        treeNode.right.right = new TreeNode(3);
-        System.out.println("Test3");
-        assertEquals("1()(2()(3))", test.tree2str(treeNode));
+        treeNode = TreeUtils.constructBinaryTree(Arrays.asList(1, null, 2, null, 3));
+        assertEquals("1()(2()(3))", solution1.tree2str(treeNode));
+        assertEquals("1()(2()(3))", solution2.tree2str(treeNode));
     }
 }