Update solution 0543

leetcode/0543.Diameter-of-Binary-Tree/543. Diameter of Binary Tree.go

@@ -18,9 +18,7 @@ type TreeNode = structures.TreeNode
 
 func diameterOfBinaryTree(root *TreeNode) int {
 	result := 0
-
 	checkDiameter(root, &result)
-
 	return result
 }
 
@@ -28,13 +26,9 @@ func checkDiameter(root *TreeNode, result *int) int {
 	if root == nil {
 		return 0
 	}
-
 	left := checkDiameter(root.Left, result)
-
 	right := checkDiameter(root.Right, result)
-
 	*result = max(*result, left+right)
-
 	return max(left, right) + 1
 }
 
@@ -42,6 +36,5 @@ func max(a int, b int) int {
 	if a > b {
 		return a
 	}
-
 	return b
 }

leetcode/0543.Diameter-of-Binary-Tree/README.md

@@ -1,12 +1,13 @@
 # [543. Diameter of Binary Tree](https://leetcode.com/problems/diameter-of-binary-tree/)
 
+
 ## 题目
 
-Given the `root` of a binary tree, return the length of the **diameter** of the tree.
+Given the `root` of a binary tree, return *the length of the **diameter** of the tree*.
 
-The **diameter** of a binary tree is the **length** of the longest path between any two nodes in a tree. This path may or may not pass through the `root`.
+The **diameter** of a binary tree is the **length** of the longest path between any two nodes in a tree. This path may or may not pass through the `root`.
 
-The **length** of a path between two nodes is represented by the number of edges between them.
+The **length** of a path between two nodes is represented by the number of edges between them.
 
 **Example 1:**
 
@@ -16,6 +17,7 @@ The **length** of a path between two nodes is represented by the number of edges
 Input: root = [1,2,3,4,5]
 Output: 3
 Explanation: 3 is the length of the path [4,2,1,3] or [5,2,1,3].
+
 ```
 
 **Example 2:**
@@ -23,9 +25,63 @@ Explanation: 3 is the length of the path [4,2,1,3] or [5,2,1,3].
 ```
 Input: root = [1,2]
 Output: 1
+
 ```
 
 **Constraints:**
 
-- The number of nodes in the tree is in the range `[1, 104]`.
-- `-100 <= Node.val <= 100`
+- The number of nodes in the tree is in the range `[1, 104]`.
+- `100 <= Node.val <= 100`
+
+## 题目大意
+
+给定一棵二叉树，你需要计算它的直径长度。一棵二叉树的直径长度是任意两个结点路径长度中的最大值。这条路径可能穿过也可能不穿过根结点。
+
+## 解题思路
+
+- 简单题。遍历每个节点的左子树和右子树，累加从左子树到右子树的最大长度。遍历每个节点时，动态更新这个最大长度即可。
+
+## 代码
+
+```go
+package leetcode
+
+import (
+	"github.com/halfrost/LeetCode-Go/structures"
+)
+
+// TreeNode define
+type TreeNode = structures.TreeNode
+
+/**
+ * Definition for a binary tree node.
+ * type TreeNode struct {
+ *     Val int
+ *     Left *TreeNode
+ *     Right *TreeNode
+ * }
+ */
+
+func diameterOfBinaryTree(root *TreeNode) int {
+	result := 0
+	checkDiameter(root, &result)
+	return result
+}
+
+func checkDiameter(root *TreeNode, result *int) int {
+	if root == nil {
+		return 0
+	}
+	left := checkDiameter(root.Left, result)
+	right := checkDiameter(root.Right, result)
+	*result = max(*result, left+right)
+	return max(left, right) + 1
+}
+
+func max(a int, b int) int {
+	if a > b {
+		return a
+	}
+	return b
+}
+```