fd

Author: dingjikerbo

README.md

@@ -377,5 +377,6 @@
 |637|[Average of Levels in Binary Tree](https://leetcode.com/problems/average-of-levels-in-binary-tree/#/description)| [Java](leetcode/solution/src/AverageOfLevelsInBinaryTree.java)|100||
 |652|[Find Duplicate Subtrees](https://leetcode.com/problems/find-duplicate-subtrees/)| [Java](leetcode/solution/src/FindDuplicateSubtrees.java)|70|开始还没思路|
 |653|[Two Sum IV - Input is a BST](https://leetcode.com/problems/two-sum-iv-input-is-a-bst/)| [Java](leetcode/solution/src/TwoSumIV.java)|90||
+|654|[Maximum Binary Tree](https://leetcode.com/problems/maximum-binary-tree/description/)|[Java](leetcode/solution/src/MaximumBinaryTree.java)|100||
 |669|[Trim a Binary Search Tree](https://leetcode.com/problems/trim-a-binary-search-tree/)|[Java](leetcode/solution/src/TrimABinarySearchTree.java)|100||
 |684|[Redundant Connection](https://leetcode.com/problems/redundant-connection/)| [Java](leetcode/solution/src/RedundantConnection.java)|||

leetcode/solution/src/MaximumBinaryTree.java

@@ -0,0 +1,22 @@
+public class MaximumBinaryTree {
+
+    public TreeNode constructMaximumBinaryTree(int[] nums, int start, int end) {
+        if (start > end) {
+            return null;
+        }
+        int max = start;
+        for (int i = start + 1; i <= end; i++) {
+            if (nums[i] > nums[max]) {
+                max = i;
+            }
+        }
+        TreeNode root = new TreeNode(nums[max]);
+        root.left = constructMaximumBinaryTree(nums, start, max - 1);
+        root.right = constructMaximumBinaryTree(nums, max + 1, end);
+        return root;
+    }
+
+    public TreeNode constructMaximumBinaryTree(int[] nums) {
+        return constructMaximumBinaryTree(nums, 0, nums.length - 1);
+    }
+}

leetcode/src/Main.java

@@ -4,17 +4,24 @@
 
 public class Main {
 
-    public int countNodes(TreeNode root) {
-        if (root == null) {
-            return 0;
+    public TreeNode constructMaximumBinaryTree(int[] nums, int start, int end) {
+        if (start > end) {
+            return null;
         }
-        int left = 0, right = 0;
-        for (TreeNode node = root; node != null; node = node.left, left++);
-        for (TreeNode node = root; node != null; node = node.right, right++);
-        if (left == right) {
-            return (1 << left) - 1;
+        int max = start;
+        for (int i = start + 1; i <= end; i++) {
+            if (nums[i] > nums[max]) {
+                max = i;
+            }
         }
-        return countNodes(root.left) + countNodes(root.right) + 1;
+        TreeNode root = new TreeNode(nums[max]);
+        root.left = constructMaximumBinaryTree(nums, start, max - 1);
+        root.right = constructMaximumBinaryTree(nums, max + 1, end);
+        return root;
+    }
+
+    public TreeNode constructMaximumBinaryTree(int[] nums) {
+        return constructMaximumBinaryTree(nums, 0, nums.length - 1);
     }
 
     public static void main(String[] args) {