added leetcode 297

.gitignore

@@ -1 +1,2 @@
 *.toml
+.idea

leetcode/0297.Serialize-and-Deserialize-Binary-Tree/297.Serialize and Deserialize Binary Tree.go

@@ -0,0 +1,58 @@
+package leetcode
+
+import (
+	"strconv"
+	"strings"
+
+	"github.com/halfrost/LeetCode-Go/structures"
+)
+
+type TreeNode = structures.TreeNode
+
+type Codec struct {
+	builder strings.Builder
+	input []string
+}
+
+func Constructor() Codec {
+	return Codec{}
+}
+
+// Serializes a tree to a single string.
+func (this *Codec) serialize(root *TreeNode) string {
+	if root == nil {
+		this.builder.WriteString("#,")
+		return ""
+	}
+
+	this.builder.WriteString(strconv.Itoa(root.Val)+",")
+	this.serialize(root.Left)
+	this.serialize(root.Right)
+
+	return this.builder.String()
+}
+
+// Deserializes your encoded data to tree.
+func (this *Codec) deserialize(data string) *TreeNode {
+	if len(data) == 0 {
+		return nil
+	}
+	this.input = strings.Split(data, ",")
+	return this.deserializeHelper()
+}
+
+func (this *Codec) deserializeHelper() *TreeNode {
+	if this.input[0] == "#" {
+		this.input = this.input[1:]
+		return nil
+	}
+
+	val, _ := strconv.Atoi(this.input[0])
+	this.input = this.input[1:]
+
+	return &TreeNode{
+		Val: val,
+		Left: this.deserializeHelper(),
+		Right: this.deserializeHelper(),
+	}
+}

leetcode/0297.Serialize-and-Deserialize-Binary-Tree/297.Serialize and Deserialize Binary Tree_test.go

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+package leetcode
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/halfrost/LeetCode-Go/structures"
+)
+
+type question297 struct {
+	para297
+	ans297
+}
+
+// para 是参数
+// one 代表第一个参数
+type para297 struct {
+	one []int
+}
+
+// ans 是答案
+// one 代表第一个答案
+type ans297 struct {
+	one []int
+}
+
+func Test_Problem297(t *testing.T) {
+	qs := []question297{
+		{
+			para297{[]int{}},
+			ans297{[]int{}},
+		},
+		{
+			para297{[]int{1,2,3,-1,-1,4,5}},
+			ans297{[]int{1,2,3,-1,-1,4,5}},
+		},
+		{
+			para297{[]int{1,2}},
+			ans297{[]int{1,2}},
+		},
+	}
+
+	fmt.Printf("------------------------Leetcode Problem 297------------------------\n")
+
+	for _, q := range qs {
+		_, p := q.ans297, q.para297
+		fmt.Printf("【input】:%v      ", p)
+		root := structures.Ints2TreeNode(p.one)
+
+		tree297 := Constructor()
+		serialized := tree297.serialize(root)
+		fmt.Printf("【output】:%v      \n", structures.Tree2Preorder(tree297.deserialize(serialized)))
+	}
+	fmt.Printf("\n\n\n")
+}

leetcode/0297.Serialize-and-Deserialize-Binary-Tree/README.md

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+# [297. Serialize and Deserialize Binary Tree](https://leetcode.com/problems/serialize-and-deserialize-binary-tree/)
+
+## 题目
+
+Serialization is the process of converting a data structure or object into a sequence of bits so that it can be stored in a file or memory buffer, or transmitted across a network connection link to be reconstructed later in the same or another computer environment.
+
+Design an algorithm to serialize and deserialize a binary tree. There is no restriction on how your serialization/deserialization algorithm should work. You just need to ensure that a binary tree can be serialized to a string and this string can be deserialized to the original tree structure.
+
+**Clarification:** The input/output format is the same as how LeetCode serializes a binary tree. You do not necessarily need to follow this format, so please be creative and come up with different approaches yourself.
+
+Example 1:
+
+```
+Input: root = [1,2,3,null,null,4,5]
+Output: [1,2,3,null,null,4,5]
+```
+
+Example 2:
+
+```
+Input: root = []
+Output: []
+```
+
+Example 3:
+
+```
+Input: root = [1]
+Output: [1]
+```
+
+Example 4:
+
+```
+Input: root = [1,2]
+Output: [1,2]
+```
+
+Constraints:
+
+* The number of nodes in the tree is in the range [0, 104].
+* -1000 <= Node.val <= 1000
+
+## 题目大意
+
+设计一个算法，来序列化和反序列化二叉树。并不限制如何进行序列化和反序列化，但是你需要保证二叉树可以序列化为字符串，并且这个字符串可以被反序列化成原有的二叉树。
+
+## 解题思路
+
+1. 将给定的二叉树想象成一颗满二叉树(不存在的结点用 null 填充)。
+2. 通过前序遍历，可以得到一个第一个结点为根的序列，然后递归进行序列化/反序列化即可。