Update solution 0106

Author: halfrost

leetcode/0106.Construct-Binary-Tree-from-Inorder-and-Postorder-Traversal/106. Construct Binary Tree from Inorder and Postorder Traversal.go

@@ -16,7 +16,25 @@ type TreeNode = structures.TreeNode
  * }
  */
 
+// 解法一, 直接传入需要的 slice 范围作为输入, 可以避免申请对应 inorder 索引的内存, 内存使用(leetcode test case) 4.7MB -> 4.3MB.
 func buildTree(inorder []int, postorder []int) *TreeNode {
+	postorderLen := len(postorder)
+	if len(inorder) == 0 {
+		return nil
+	}
+	root := &TreeNode{Val: postorder[postorderLen-1]}
+	postorder = postorder[:postorderLen-1]
+	for pos, node := range inorder {
+		if node == root.Val {
+			root.Left = buildTree(inorder[:pos], postorder[:len(inorder[:pos])])
+			root.Right = buildTree(inorder[pos+1:], postorder[len(inorder[:pos]):])
+		}
+	}
+	return root
+}
+
+// 解法二
+func buildTree1(inorder []int, postorder []int) *TreeNode {
 	inPos := make(map[int]int)
 	for i := 0; i < len(inorder); i++ {
 		inPos[inorder[i]] = i

website/content/ChapterFour/0100~0199/0106.Construct-Binary-Tree-from-Inorder-and-Postorder-Traversal.md

@@ -40,6 +40,13 @@ Return the following binary tree:
 
 package leetcode
 
+import (
+	"github.com/halfrost/LeetCode-Go/structures"
+)
+
+// TreeNode define
+type TreeNode = structures.TreeNode
+
 /**
  * Definition for a binary tree node.
  * type TreeNode struct {
@@ -48,7 +55,26 @@ package leetcode
  *     Right *TreeNode
  * }
  */
+
+// 解法一, 直接传入需要的 slice 范围作为输入, 可以避免申请对应 inorder 索引的内存, 内存使用(leetcode test case) 4.7MB -> 4.3MB.
 func buildTree(inorder []int, postorder []int) *TreeNode {
+	postorderLen := len(postorder)
+	if len(inorder) == 0 {
+		return nil
+	}
+	root := &TreeNode{Val: postorder[postorderLen-1]}
+	postorder = postorder[:postorderLen-1]
+	for pos, node := range inorder {
+		if node == root.Val {
+			root.Left = buildTree(inorder[:pos], postorder[:len(inorder[:pos])])
+			root.Right = buildTree(inorder[pos+1:], postorder[len(inorder[:pos]):])
+		}
+	}
+	return root
+}
+
+// 解法二
+func buildTree1(inorder []int, postorder []int) *TreeNode {
 	inPos := make(map[int]int)
 	for i := 0; i < len(inorder); i++ {
 		inPos[inorder[i]] = i
@@ -68,22 +94,7 @@ func buildInPos2TreeDFS(post []int, postStart int, postEnd int, inStart int, inP
 	return root
 }
 
-// 解法 2, 直接传入需要的 slice 范围作为输入, 可以避免申请对应 inorder 索引的内存, 内存使用(leetcode test case) 4.7MB -> 4.3MB.
-func buildTree(inorder []int, postorder []int) *TreeNode {
-	postorderLen := len(postorder)
-    if len(inorder) == 0 { 
-    	return nil 
-    }
-    root := &TreeNode{Val:postorder[postorderLen-1]}
-    postorder = postorder[:postorderLen-1]
-    for pos, node := range inorder {
-    	if node == root.Val {
-    		root.Left  = buildTree(inorder[:pos], postorder[:len(inorder[:pos])])
-    		root.Right = buildTree(inorder[pos+1:], postorder[len(inorder[:pos]):])
-    	}
-    }
-    return root
-}
+
 ```