fd

Author: dingjikerbo

README.md

@@ -371,6 +371,7 @@
 |526|[Beautiful Arrangement](https://leetcode.com/problems/beautiful-arrangement/)| [Java](leetcode/solution/src/BeautifulArrangement.java)|80||
 |535|[Encode and Decode TinyURL](https://leetcode.com/problems/encode-and-decode-tinyurl/)| [Java](leetcode/solution/src/EncodeAndDecodeTinyURL.java)|100||
 |541|[Reverse String II](https://leetcode.com/problems/reverse-string-ii/)| [Java](leetcode/solution/src/ReverseStringII.java)|100||
+|543|[Diameter of Binary Tree](https://leetcode.com/problems/diameter-of-binary-tree/)|[Java](leetcode/solution/src/DiameterOfBinaryTree.java)|80|这题易错|
 |557|[Reverse Words in a String III](https://leetcode.com/problems/reverse-words-in-a-string-iii/)| [Java](leetcode/solution/src/ReverseWordsInAStringIII.java)|100||
 |560|[Subarray Sum Equals K](https://leetcode.com/problems/subarray-sum-equals-k/)| [Java](leetcode/solution/src/SubarraySumEqualsK.java)|70||
 |617|[Merge Two Binary Trees](https://leetcode.com/problems/merge-two-binary-trees/)|[Java](leetcode/solution/src/MergeTwoBinaryTrees.java)|100|很简单|

leetcode/out/production/leetcode/Main.class

@@ -0,0 +1,24 @@
+public class DiameterOfBinaryTree {
+
+    /**
+     * 这题和 124. Binary Tree Maximum Path Sum比较像
+     * 都是分两种情况，一种是必须包括root的，带上必须包括left和right的单边结果;
+     * 还有不是必须包括root的，对比left和right的双边结果
+     * flag为true表示必须包括root，false表示不是必须包括root
+     */
+    public int diameterOfBinaryTree(TreeNode root) {
+        if (root == null) {
+            return 0;
+        }
+        return dfs(root, false);
+    }
+
+    public int dfs(TreeNode root, boolean flag) {
+        if (root == null) {
+            return -1;
+        }
+        return flag ? Math.max(dfs(root.left, true) + 1, dfs(root.right, true) + 1) :
+                Math.max(Math.max(dfs(root.left, false), dfs(root.right, false)),
+                        dfs(root.left, true) + 2 + dfs(root.right, true));
+    }
+}

leetcode/out/production/solution/BinaryTreeInorderTraversal.class

@@ -4,44 +4,29 @@
 
 public class Main {
 
-    public List<Integer> rightSideView(TreeNode root) {
-        List<Integer> result = new LinkedList<>();
-
+    public static int diameterOfBinaryTree(TreeNode root) {
         if (root == null) {
-            return result;
+            return 0;
         }
+        return dfs(root, false);
+    }
 
-        Queue<TreeNode> queue = new LinkedList<>();
-        Queue<TreeNode> next = new LinkedList<>();
-
-        TreeNode last = null;
-
-        queue.offer(root);
-
-        while (!queue.isEmpty()) {
-            TreeNode node = queue.poll();
-
-            last = node;
-
-            if (node.left != null) {
-                next.offer(node.left);
-            }
-
-            if (node.right != null) {
-                next.offer(node.right);
-            }
-
-            if (queue.isEmpty()) {
-                queue.addAll(next);
-                next.clear();
-                result.add(last.val);
-            }
+    public static int dfs(TreeNode root, boolean flag) {
+        if (root == null) {
+            return -1;
         }
-
-        return result;
+        return flag ? Math.max(dfs(root.left, true) + 1, dfs(root.right, true) + 1) :
+                Math.max(Math.max(dfs(root.left, false), dfs(root.right, false)),
+                        dfs(root.left, true) + 2 + dfs(root.right, true));
     }
 
     public static void main(String[] args) {
-
+        TreeNode node4 = new TreeNode(4);
+        TreeNode node5 = new TreeNode(5);
+        TreeNode node2 = new TreeNode(2, node4, node5);
+        TreeNode node3 = new TreeNode(3);
+        TreeNode node1 = new TreeNode(1, node2, node3);
+        int len = diameterOfBinaryTree(node1);
+        System.out.println(String.format("len = %d", len));
     }
 }