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Update solution 0105

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halfrost
2021-07-30 21:21:21 +08:00
parent 3de30e7848
commit c1d27a197b
2 changed files with 40 additions and 14 deletions
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16
leetcode/0105.Construct-Binary-Tree-from-Preorder-and-Inorder-Traversal/105. Construct Binary Tree from Preorder and Inorder Traversal.go
View File

@ -16,7 +16,23 @@ 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(preorder []int, inorder []int) *TreeNode { func buildTree(preorder []int, inorder []int) *TreeNode {
if len(preorder) == 0 {
return nil
}
root := &TreeNode{Val: preorder[0]}
for pos, node := range inorder {
if node == root.Val {
root.Left = buildTree(preorder[1:pos+1], inorder[:pos])
root.Right = buildTree(preorder[pos+1:], inorder[pos+1:])
}
}
return root
}
// 解法二
func buildTree1(preorder []int, inorder []int) *TreeNode {
inPos := make(map[int]int) inPos := make(map[int]int)
for i := 0; i < len(inorder); i++ { for i := 0; i < len(inorder); i++ {
inPos[inorder[i]] = i inPos[inorder[i]] = i

38
website/content/ChapterFour/0100~0199/0105.Construct-Binary-Tree-from-Preorder-and-Inorder-Traversal.md
View File

@ -42,6 +42,13 @@ Return the following binary tree:
package leetcode package leetcode
import (
"github.com/halfrost/LeetCode-Go/structures"
)
// TreeNode define
type TreeNode = structures.TreeNode
/** /**
* Definition for a binary tree node. * Definition for a binary tree node.
* type TreeNode struct { * type TreeNode struct {
@ -50,7 +57,24 @@ package leetcode
* Right *TreeNode * 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(preorder []int, inorder []int) *TreeNode { func buildTree(preorder []int, inorder []int) *TreeNode {
if len(preorder) == 0 {
return nil
}
root := &TreeNode{Val: preorder[0]}
for pos, node := range inorder {
if node == root.Val {
root.Left = buildTree(preorder[1:pos+1], inorder[:pos])
root.Right = buildTree(preorder[pos+1:], inorder[pos+1:])
}
}
return root
}
// 解法二
func buildTree1(preorder []int, inorder []int) *TreeNode {
inPos := make(map[int]int) inPos := make(map[int]int)
for i := 0; i < len(inorder); i++ { for i := 0; i < len(inorder); i++ {
inPos[inorder[i]] = i inPos[inorder[i]] = i
@ -70,20 +94,6 @@ func buildPreIn2TreeDFS(pre []int, preStart int, preEnd int, inStart int, inPos
return root 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(preorder []int, inorder []int) *TreeNode {
if len(preorder) == 0 {
return nil
}
root := &TreeNode{Val:preorder[0]}
for pos, node := range inorder {
if node == root.Val {
root.Left = buildTree(preorder[1:pos+1], inorder[:pos])
root.Right = buildTree(preorder[pos+1:], inorder[pos+1:])
}
}
return root
}
``` ```