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Author: dingjikerbo

leetcode/solution/src/HouseRobberIII.java

@@ -25,6 +25,8 @@ private int rob(TreeNode root, boolean rob) {
 
     /**
      * 优化写法如下，耗时1ms
+     * 这里将两种情况都保存下来并返回给上层，避免了多次重复计算
+     * val[0]表示不rob当前节点，val[1]表示rob当前节点
      */
     public int rob2(TreeNode root) {
         int[] val = helper(root);

leetcode/src/Main.java

@@ -6,27 +6,8 @@ public class Main {
 
     public static class Solution {
 
-        public int diameterOfBinaryTree(TreeNode root) {
-            if (root == null) {
-                return 0;
-            }
-            return dfs(root, new int[1]) - 1;
-        }
-
-        private int dfs(TreeNode root, int[] len) {
-            if (root == null) {
-                return 0;
-            }
-
-            int[] lt = new int[1];
-            int[] rt = new int[1];
-
-            int left = dfs(root.left, lt);
-            int right = dfs(root.right, rt);
-
-            len[0] = Math.max(lt[0], rt[0]) + 1;
+        public List<TreeNode> generateTrees(int n) {
 
-            return Math.max(Math.max(left, right), lt[0] + rt[0] + 1);
         }
     }