Merge pull request #29 from Reanon/feature/support-go-chapter-tree
Support go code in chapter-tree
This commit is contained in:
commit
62c40fdf1b
@ -1,5 +1,5 @@
|
||||
// File: binary_search_tree.go
|
||||
// Created Time: 2022-11-25
|
||||
// Created Time: 2022-11-26
|
||||
// Author: Reanon (793584285@qq.com)
|
||||
|
||||
package chapter_tree
|
||||
@ -14,7 +14,166 @@ type BinarySearchTree struct {
|
||||
}
|
||||
|
||||
func NewBinarySearchTree(nums []int) *BinarySearchTree {
|
||||
// 排序数组
|
||||
// sorting array
|
||||
sort.Ints(nums)
|
||||
return nil
|
||||
root := buildBinarySearchTree(nums, 0, len(nums)-1)
|
||||
return &BinarySearchTree{
|
||||
root: root,
|
||||
}
|
||||
}
|
||||
|
||||
// GetRoot Get the root node of binary search tree
|
||||
func (bst *BinarySearchTree) GetRoot() *TreeNode {
|
||||
return bst.root
|
||||
}
|
||||
|
||||
// GetMin Get node with the min value
|
||||
func (bst *BinarySearchTree) GetMin(node *TreeNode) *TreeNode {
|
||||
if node == nil {
|
||||
return node
|
||||
}
|
||||
// 循环访问左子结点,直到叶结点时为最小结点,跳出
|
||||
for node.Left != nil {
|
||||
node = node.Left
|
||||
}
|
||||
return node
|
||||
}
|
||||
|
||||
// GetInorderNext Get node inorder next
|
||||
func (bst *BinarySearchTree) GetInorderNext(node *TreeNode) *TreeNode {
|
||||
if node == nil || node.Right == nil {
|
||||
return node
|
||||
}
|
||||
node = node.Right
|
||||
// 循环访问左子结点,直到叶结点时为最小结点,跳出
|
||||
for node.Left != nil {
|
||||
node = node.Left
|
||||
}
|
||||
return node
|
||||
}
|
||||
|
||||
// Search node of binary search tree
|
||||
func (bst *BinarySearchTree) Search(num int) *TreeNode {
|
||||
node := bst.root
|
||||
// 循环查找,越过叶结点后跳出
|
||||
for node != nil {
|
||||
if node.Val < num {
|
||||
// 目标结点在 root 的右子树中
|
||||
node = node.Right
|
||||
} else if node.Val > num {
|
||||
// 目标结点在 root 的左子树中
|
||||
node = node.Left
|
||||
} else {
|
||||
// 找到目标结点,跳出循环
|
||||
break
|
||||
}
|
||||
}
|
||||
// 返回目标结点
|
||||
return node
|
||||
}
|
||||
|
||||
// Insert node of binary search tree
|
||||
func (bst *BinarySearchTree) Insert(num int) *TreeNode {
|
||||
cur := bst.root
|
||||
// 若树为空,直接提前返回
|
||||
if cur == nil {
|
||||
return nil
|
||||
}
|
||||
// 待插入结点之前的结点位置
|
||||
var prev *TreeNode = nil
|
||||
// 循环查找,越过叶结点后跳出
|
||||
for cur != nil {
|
||||
if cur.Val == num {
|
||||
return nil
|
||||
}
|
||||
prev = cur
|
||||
if cur.Val < num {
|
||||
cur = cur.Right
|
||||
} else {
|
||||
cur = cur.Left
|
||||
}
|
||||
}
|
||||
// 插入结点
|
||||
node := NewTreeNode(num)
|
||||
if prev.Val < num {
|
||||
prev.Right = node
|
||||
} else {
|
||||
prev.Left = node
|
||||
}
|
||||
return cur
|
||||
}
|
||||
|
||||
// Remove node of binary search tree
|
||||
func (bst *BinarySearchTree) Remove(num int) *TreeNode {
|
||||
cur := bst.root
|
||||
// 若树为空,直接提前返回
|
||||
if cur == nil {
|
||||
return nil
|
||||
}
|
||||
// 待删除结点之前的结点位置
|
||||
var prev *TreeNode = nil
|
||||
// 循环查找,越过叶结点后跳出
|
||||
for cur != nil {
|
||||
if cur.Val == num {
|
||||
break
|
||||
}
|
||||
prev = cur
|
||||
// 待删除结点在右子树中
|
||||
if cur.Val < num {
|
||||
cur = cur.Right
|
||||
} else {
|
||||
// 待删除结点在左子树中
|
||||
cur = cur.Left
|
||||
}
|
||||
}
|
||||
// 若无待删除结点,则直接返回
|
||||
if cur == nil {
|
||||
return nil
|
||||
}
|
||||
// 子结点数为 0 或 1
|
||||
if cur.Left == nil || cur.Right == nil {
|
||||
var child *TreeNode = nil
|
||||
// 取出待删除结点的子结点
|
||||
if cur.Left != nil {
|
||||
child = cur.Left
|
||||
} else {
|
||||
child = cur.Right
|
||||
}
|
||||
// 将子结点替换为待删除结点
|
||||
if prev.Left == cur {
|
||||
prev.Left = child
|
||||
} else {
|
||||
prev.Right = child
|
||||
}
|
||||
|
||||
} else { // 子结点数为 2
|
||||
// 获取中序遍历中待删除结点 cur 的下一个结点
|
||||
next := bst.GetInorderNext(cur)
|
||||
temp := next.Val
|
||||
// 递归删除结点 next
|
||||
bst.Remove(next.Val)
|
||||
// 将 next 的值复制给 cur
|
||||
cur.Val = temp
|
||||
}
|
||||
// TODO: add error handler, don't return node
|
||||
return cur
|
||||
}
|
||||
|
||||
// buildBinarySearchTree Build a binary search tree from array.
|
||||
func buildBinarySearchTree(nums []int, left, right int) *TreeNode {
|
||||
if left > right {
|
||||
return nil
|
||||
}
|
||||
// 将数组中间结点作为根结点
|
||||
middle := left + (right-left)>>1
|
||||
root := NewTreeNode(nums[middle])
|
||||
// 递归构建左子树和右子树
|
||||
root.Left = buildBinarySearchTree(nums, left, middle-1)
|
||||
root.Right = buildBinarySearchTree(nums, middle+1, right)
|
||||
return root
|
||||
}
|
||||
|
||||
// Print binary search tree
|
||||
func (bst *BinarySearchTree) Print() {
|
||||
PrintTree(bst.root)
|
||||
}
|
||||
|
41
codes/go/chapter_tree/binary_search_tree_test.go
Normal file
41
codes/go/chapter_tree/binary_search_tree_test.go
Normal file
@ -0,0 +1,41 @@
|
||||
// File: binary_search_tree_test.go
|
||||
// Created Time: 2022-11-26
|
||||
// Author: Reanon (793584285@qq.com)
|
||||
|
||||
package chapter_tree
|
||||
|
||||
import "testing"
|
||||
|
||||
func TestBinarySearchTree(t *testing.T) {
|
||||
nums := []int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15}
|
||||
bst := NewBinarySearchTree(nums)
|
||||
t.Log("初始化的二叉树为: ")
|
||||
bst.Print()
|
||||
|
||||
// 获取根结点
|
||||
node := bst.GetRoot()
|
||||
t.Log("二叉树的根结点为: ", node.Val)
|
||||
// 获取最小的结点
|
||||
node = bst.GetMin(bst.GetRoot())
|
||||
t.Log("二叉树的最小结点为: ", node.Val)
|
||||
|
||||
// 查找结点
|
||||
node = bst.Search(5)
|
||||
t.Log("查找到的结点对象为", node, ",结点值 = ", node.Val)
|
||||
|
||||
// 插入结点
|
||||
node = bst.Insert(16)
|
||||
t.Log("插入结点后 16 的二叉树为: ")
|
||||
bst.Print()
|
||||
|
||||
// 删除结点
|
||||
bst.Remove(1)
|
||||
t.Log("删除结点 1 后的二叉树为: ")
|
||||
bst.Print()
|
||||
bst.Remove(2)
|
||||
t.Log("删除结点 2 后的二叉树为: ")
|
||||
bst.Print()
|
||||
bst.Remove(4)
|
||||
t.Log("删除结点 4 后的二叉树为: ")
|
||||
bst.Print()
|
||||
}
|
35
codes/go/chapter_tree/binary_tree_bfs.go
Normal file
35
codes/go/chapter_tree/binary_tree_bfs.go
Normal file
@ -0,0 +1,35 @@
|
||||
// File: binary_tree_bfs.go
|
||||
// Created Time: 2022-11-26
|
||||
// Author: Reanon (793584285@qq.com)
|
||||
|
||||
package chapter_tree
|
||||
|
||||
import (
|
||||
"container/list"
|
||||
. "github.com/krahets/hello-algo/pkg"
|
||||
)
|
||||
|
||||
// levelOrder Breadth First Search
|
||||
func levelOrder(root *TreeNode) []int {
|
||||
// Let container.list as queue
|
||||
queue := list.New()
|
||||
// 初始化队列,加入根结点
|
||||
queue.PushBack(root)
|
||||
// 初始化一个切片,用于保存遍历序列
|
||||
nums := make([]int, 0)
|
||||
for queue.Len() > 0 {
|
||||
// poll
|
||||
node := queue.Remove(queue.Front()).(*TreeNode)
|
||||
// 保存结点
|
||||
nums = append(nums, node.Val)
|
||||
if node.Left != nil {
|
||||
// 左子结点入队
|
||||
queue.PushBack(node.Left)
|
||||
}
|
||||
if node.Right != nil {
|
||||
// 右子结点入队
|
||||
queue.PushBack(node.Right)
|
||||
}
|
||||
}
|
||||
return nums
|
||||
}
|
22
codes/go/chapter_tree/binary_tree_bfs_test.go
Normal file
22
codes/go/chapter_tree/binary_tree_bfs_test.go
Normal file
@ -0,0 +1,22 @@
|
||||
// File: binary_tree_bfs_test.go
|
||||
// Created Time: 2022-11-26
|
||||
// Author: Reanon (793584285@qq.com)
|
||||
|
||||
package chapter_tree
|
||||
|
||||
import (
|
||||
. "github.com/krahets/hello-algo/pkg"
|
||||
"testing"
|
||||
)
|
||||
|
||||
func TestLevelOrder(t *testing.T) {
|
||||
/* 初始化二叉树 */
|
||||
// 这里借助了一个从数组直接生成二叉树的函数
|
||||
root := ArrayToTree([]int{1, 2, 3, 4, 5, 6, 7})
|
||||
t.Log("初始化二叉树: ")
|
||||
PrintTree(root)
|
||||
|
||||
// 层序遍历
|
||||
nums := levelOrder(root)
|
||||
t.Log("层序遍历的结点打印序列 = ", nums)
|
||||
}
|
63
codes/go/chapter_tree/binary_tree_dfs.go
Normal file
63
codes/go/chapter_tree/binary_tree_dfs.go
Normal file
@ -0,0 +1,63 @@
|
||||
// File: binary_tree_dfs.go
|
||||
// Created Time: 2022-11-26
|
||||
// Author: Reanon (793584285@qq.com)
|
||||
|
||||
package chapter_tree
|
||||
|
||||
import (
|
||||
. "github.com/krahets/hello-algo/pkg"
|
||||
)
|
||||
|
||||
// preOrder 前序遍历
|
||||
func preOrder(root *TreeNode) (nums []int) {
|
||||
var preOrderHelper func(node *TreeNode)
|
||||
// 匿名函数
|
||||
preOrderHelper = func(node *TreeNode) {
|
||||
if node == nil {
|
||||
return
|
||||
}
|
||||
// 访问优先级:根结点 -> 左子树 -> 右子树
|
||||
nums = append(nums, node.Val)
|
||||
preOrderHelper(node.Left)
|
||||
preOrderHelper(node.Right)
|
||||
}
|
||||
// 函数调用
|
||||
preOrderHelper(root)
|
||||
return
|
||||
}
|
||||
|
||||
// inOrder 中序遍历
|
||||
func inOrder(root *TreeNode) (nums []int) {
|
||||
var inOrderHelper func(node *TreeNode)
|
||||
// 匿名函数
|
||||
inOrderHelper = func(node *TreeNode) {
|
||||
if node == nil {
|
||||
return
|
||||
}
|
||||
// 访问优先级:左子树 -> 根结点 -> 右子树
|
||||
inOrderHelper(node.Left)
|
||||
nums = append(nums, node.Val)
|
||||
inOrderHelper(node.Right)
|
||||
}
|
||||
// 函数调用
|
||||
inOrderHelper(root)
|
||||
return
|
||||
}
|
||||
|
||||
// postOrder 后序遍历
|
||||
func postOrder(root *TreeNode) (nums []int) {
|
||||
var postOrderHelper func(node *TreeNode)
|
||||
// 匿名函数
|
||||
postOrderHelper = func(node *TreeNode) {
|
||||
if node == nil {
|
||||
return
|
||||
}
|
||||
// 访问优先级:左子树 -> 右子树 -> 根结点
|
||||
postOrderHelper(node.Left)
|
||||
postOrderHelper(node.Right)
|
||||
nums = append(nums, node.Val)
|
||||
}
|
||||
// 函数调用
|
||||
postOrderHelper(root)
|
||||
return
|
||||
}
|
30
codes/go/chapter_tree/binary_tree_dfs_test.go
Normal file
30
codes/go/chapter_tree/binary_tree_dfs_test.go
Normal file
@ -0,0 +1,30 @@
|
||||
// File: binary_tree_dfs_test.go
|
||||
// Created Time: 2022-11-26
|
||||
// Author: Reanon (793584285@qq.com)
|
||||
|
||||
package chapter_tree
|
||||
|
||||
import (
|
||||
. "github.com/krahets/hello-algo/pkg"
|
||||
"testing"
|
||||
)
|
||||
|
||||
func TestPreInPostOrderTraversal(t *testing.T) {
|
||||
/* 初始化二叉树 */
|
||||
// 这里借助了一个从数组直接生成二叉树的函数
|
||||
root := ArrayToTree([]int{1, 2, 3, 4, 5, 6, 7})
|
||||
t.Log("初始化二叉树: ")
|
||||
PrintTree(root)
|
||||
|
||||
// 前序遍历
|
||||
nums := preOrder(root)
|
||||
t.Log("前序遍历的结点打印序列 = ", nums)
|
||||
|
||||
// 中序遍历
|
||||
nums = inOrder(root)
|
||||
t.Log("中序遍历的结点打印序列 = ", nums)
|
||||
|
||||
// 后序遍历
|
||||
nums = postOrder(root)
|
||||
t.Log("后序遍历的结点打印序列 = ", nums)
|
||||
}
|
@ -11,7 +11,7 @@ import (
|
||||
|
||||
func TestBinaryTree(t *testing.T) {
|
||||
/* 初始化二叉树 */
|
||||
// 初始化节点
|
||||
// 初始化结点
|
||||
n1 := NewTreeNode(1)
|
||||
n2 := NewTreeNode(2)
|
||||
n3 := NewTreeNode(3)
|
||||
|
@ -51,11 +51,11 @@ func ArrayToTree(arr []int) *TreeNode {
|
||||
}
|
||||
|
||||
// TreeToArray Serialize a binary tree to a list
|
||||
func TreeToArray(root *TreeNode) []int {
|
||||
func TreeToArray(root *TreeNode) []any {
|
||||
if root == nil {
|
||||
return []int{}
|
||||
return []any{}
|
||||
}
|
||||
arr := make([]int, 16)
|
||||
arr := make([]any, 0)
|
||||
queue := list.New()
|
||||
queue.PushBack(root)
|
||||
for queue.Len() > 0 {
|
||||
@ -65,7 +65,8 @@ func TreeToArray(root *TreeNode) []int {
|
||||
queue.PushBack(node.Left)
|
||||
queue.PushBack(node.Right)
|
||||
} else {
|
||||
arr = append(arr, -1)
|
||||
// node don't exist.
|
||||
arr = append(arr, nil)
|
||||
}
|
||||
}
|
||||
return arr
|
||||
@ -73,19 +74,19 @@ func TreeToArray(root *TreeNode) []int {
|
||||
|
||||
// PrintTree Print a binary tree
|
||||
func PrintTree(root *TreeNode) {
|
||||
PrintTreeHelper(root, nil, false)
|
||||
printTreeHelper(root, nil, false)
|
||||
}
|
||||
|
||||
// PrintTreeHelper Help to print a binary tree, hide more details
|
||||
// printTreeHelper Help to print a binary tree, hide more details
|
||||
// This tree printer is borrowed from TECHIE DELIGHT
|
||||
// https://www.techiedelight.com/c-program-print-binary-tree/
|
||||
func PrintTreeHelper(root *TreeNode, prev *trunk, isLeft bool) {
|
||||
func printTreeHelper(root *TreeNode, prev *trunk, isLeft bool) {
|
||||
if root == nil {
|
||||
return
|
||||
}
|
||||
prevStr := " "
|
||||
trunk := newTrunk(prev, prevStr)
|
||||
PrintTreeHelper(root.Right, trunk, true)
|
||||
printTreeHelper(root.Right, trunk, true)
|
||||
if prev == nil {
|
||||
trunk.str = "———"
|
||||
} else if isLeft {
|
||||
@ -101,7 +102,7 @@ func PrintTreeHelper(root *TreeNode, prev *trunk, isLeft bool) {
|
||||
prev.str = prevStr
|
||||
}
|
||||
trunk.str = " |"
|
||||
PrintTreeHelper(root.Left, trunk, false)
|
||||
printTreeHelper(root.Left, trunk, false)
|
||||
}
|
||||
|
||||
// trunk Help to Print tree structure
|
||||
|
@ -12,4 +12,7 @@ func TestTreeNode(t *testing.T) {
|
||||
|
||||
// print tree
|
||||
PrintTree(node)
|
||||
|
||||
// tree to arr
|
||||
t.Log(TreeToArray(node))
|
||||
}
|
||||
|
@ -63,11 +63,11 @@ comments: true
|
||||
|
||||
给定一个待插入元素 `num` ,为了保持二叉搜索树 “左子树 < 根结点 < 右子树” 的性质,插入操作分为两步:
|
||||
|
||||
1. **查找插入位置:** 与查找操作类似,我们从根结点出发,根据当前节点值和 `num` 的大小关系循环向下搜索,直到越过叶结点(遍历到 $\text{null}$ )时跳出循环;
|
||||
1. **查找插入位置:** 与查找操作类似,我们从根结点出发,根据当前结点值和 `num` 的大小关系循环向下搜索,直到越过叶结点(遍历到 $\text{null}$ )时跳出循环;
|
||||
|
||||
2. **在该位置插入结点:** 初始化结点 `num` ,将该结点放到 $\text{null}$ 的位置 ;
|
||||
|
||||
二叉搜索树不允许存在重复节点,否则将会违背其定义。因此若待插入结点在树中已经存在,则不执行插入,直接返回即可。
|
||||
二叉搜索树不允许存在重复结点,否则将会违背其定义。因此若待插入结点在树中已经存在,则不执行插入,直接返回即可。
|
||||
|
||||
![bst_insert](binary_search_tree.assets/bst_insert.png)
|
||||
|
||||
|
@ -24,7 +24,7 @@ comments: true
|
||||
|
||||
<p align="center"> Fig. 子结点与子树 </p>
|
||||
|
||||
需要注意,父结点、子结点、子树是可以向下递推的。例如,如果将上图的「结点 2」看作父结点,那么其左子节点和右子结点分别为「结点 4」和「结点 5」,左子树和右子树分别为「结点 4 以下的树」和「结点 5 以下的树」。
|
||||
需要注意,父结点、子结点、子树是可以向下递推的。例如,如果将上图的「结点 2」看作父结点,那么其左子结点和右子结点分别为「结点 4」和「结点 5」,左子树和右子树分别为「结点 4 以下的树」和「结点 5 以下的树」。
|
||||
|
||||
## 二叉树常见术语
|
||||
|
||||
|
Loading…
Reference in New Issue
Block a user