init commit

Author: yuanyu90221

.github/workflows/java.yml

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+name: Java
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    branches:
+      - master
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+      - name: Setup JDK 11
+        uses: actions/setup-java@v3
+        with:
+          distribution: 'adopt'
+          java-version: '11'
+      - name: Grant execution permission for gradlew
+        run: chmod +x gradlew
+      - name: Cache Gradle packages
+        uses: actions/cache@v3
+        with:
+          path: ~/.gradle/caches
+          key: ${{ runner.os }}-gradle-${{ github.event.repository.name }}-${{ hashFiles('**/*.gradle')}}
+          restore-keys: ${{ runner.os }}-gradle-${{ github.event.repository.name }}
+      - name: Build with Gradlew
+        run: ./gradlew build
+      - name: Test with Gradlew
+        run: ./gradlew :test --tests "SolutionTest"

.gitignore

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+.gradle
+build/
+!gradle/wrapper/gradle-wrapper.jar
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### IntelliJ IDEA ###
+.idea/modules.xml
+.idea/jarRepositories.xml
+.idea/compiler.xml
+.idea/libraries/
+*.iws
+*.iml
+*.ipr
+out/
+!**/src/main/**/out/
+!**/src/test/**/out/
+
+### Eclipse ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+bin/
+!**/src/main/**/bin/
+!**/src/test/**/bin/
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+
+### VS Code ###
+.vscode/
+
+### Mac OS ###
+.DS_Store

.husky/pre-commit

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+#!/bin/bash
+./gradlew :test --tests "SolutionTest"

.idea/gradle.xml

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+# java_serialize_deserialize_binary_tree
+
+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](https://leetcode.com/faq/#binary-tree). You do not necessarily need to follow this format, so please be creative and come up with different approaches yourself.
+
+## Examples
+
+**Example 1:**
+
+![https://assets.leetcode.com/uploads/2020/09/15/serdeser.jpg](https://assets.leetcode.com/uploads/2020/09/15/serdeser.jpg)
+
+```
+Input: root = [1,2,3,null,null,4,5]
+Output: [1,2,3,null,null,4,5]
+
+```
+
+**Example 2:**
+
+```
+Input: root = []
+Output: []
+
+```
+
+**Constraints:**
+
+- The number of nodes in the tree is in the range `[0, 104]`.
+- `1000 <= Node.val <= 1000`
+
+## 解析
+
+給定一個二元樹結點 root 要求要實作 serial, deserial 方法
+
+可以透過 DFS 實作 Pre-order format
+
+如下圖
+
+![](https://i.imgur.com/rMQXbOx.png)
+
+## 程式碼
+```java
+class Solution {
+  // Encodes a tree to a single string.
+  public String serialize(TreeNode root) {
+    List<String> list = new ArrayList<>();
+    DFS(root, list);
+    return String.join(",", list);
+  }
+  public void DFS(TreeNode root, List<String> list) {
+    if (root == null) {
+      list.add("N");
+      return;
+    }
+    list.add(String.valueOf(root.val));
+    DFS(root.left, list);
+    DFS(root.right, list);
+  }
+  // Decodes your encoded data to tree.
+  int count;
+  public TreeNode deserialize(String data) {
+    String[] list = data.split(",");
+    count = 0;
+    return DE_DFS(list);
+  }
+  public TreeNode DE_DFS(String[] list) {
+    if (list[count].equals("N")){
+      count++;
+      return null;
+    }
+    int rootValue = Integer.parseInt(list[count]);
+    count++;
+    TreeNode root = new TreeNode(rootValue);
+    root.left = DE_DFS(list);
+    root.right = DE_DFS(list);
+    return root;
+  }
+}
+```
+## 困難點
+
+1. Understand DFS
+
+## Solve Point
+
+- [x]  Understand what problem need to solve
+- [x]  Analysis Complexity

.idea/misc.xml

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+plugins {
+    id 'java'
+}
+
+group 'org.example'
+version '1.0-SNAPSHOT'
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    testImplementation 'org.junit.jupiter:junit-jupiter-api:5.8.1'
+    testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.8.1'
+}
+
+test {
+    useJUnitPlatform()
+}

.idea/vcs.xml

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+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.4-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists