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_target_sum_input_array_sorted
+
+Given a **1-indexed** array of integers `numbers` that is already ***sorted in non-decreasing order***, find two numbers such that they add up to a specific `target` number. Let these two numbers be `numbers[index1]` and `numbers[index2]` where `1 <= index1 < index2 <= numbers.length`.
+
+Return *the indices of the two numbers,* `index1` *and* `index2`*, **added by one** as an integer array* `[index1, index2]` *of length 2.*
+
+The tests are generated such that there is **exactly one solution**. You **may not** use the same element twice.
+
+Your solution must use only constant extra space.
+
+## Examples
+
+**Example 1:**
+
+```
+Input: numbers = [2,7,11,15], target = 9
+Output: [1,2]
+Explanation: The sum of 2 and 7 is 9. Therefore, index1 = 1, index2 = 2. We return [1, 2].
+
+```
+
+**Example 2:**
+
+```
+Input: numbers = [2,3,4], target = 6
+Output: [1,3]
+Explanation: The sum of 2 and 4 is 6. Therefore index1 = 1, index2 = 3. We return [1, 3].
+
+```
+
+**Example 3:**
+
+```
+Input: numbers = [-1,0], target = -1
+Output: [1,2]
+Explanation: The sum of -1 and 0 is -1. Therefore index1 = 1, index2 = 2. We return [1, 2].
+
+```
+
+**Constraints:**
+
+- `2 <= numbers.length <= $3 * 10^4$`
+- `1000 <= numbers[i] <= 1000`
+- `numbers` is sorted in **non-decreasing order**.
+- `1000 <= target <= 1000`
+- The tests are generated such that there is **exactly one solution**.
+
+## 解析
+
+給定一個由小到大排序過的整數陣列 numbers. 給定一個整數 target
+
+要求實作一個演算法找出 numbers 中兩個數相加合的 target
+
+並且要求空間複雜度必須要是 O(1)
+
+因為是排序過的整數陣列
+
+所以可以透過兩個 pointer , lp =0, rp = len(numbers) -1
+
+當 lp < rp 時做以下判斷
+
+當 numbers[lp] + numbers[rp] == target  則找到這兩個index 回傳 [lp + 1 , rp +1 ] // 因為題目要求是 1-indexed 的座標 而 golang 與 java 都是 0-indexed
+
+當 numbers[lp] + numbers[rp] > target 
+
+因為左界已經到最小值，所以要讓兩數相加變小只能把右界向左移 更新 rp -=1 
+
+當 numbers[lp] + numbers[rp] < target  
+
+因為左界已經到最大值，所以要讓兩數相加變大只能把左界向右移 更新 lp +=1
+
+當跑到最後都找不到則回傳 nil
+
+詳細作法如下圖
+
+![](https://i.imgur.com/knDWRGn.png)
+
+
+## 程式碼
+```java
+public class Solution {
+  public int[] twoSum(int[] numbers, int target) {
+    int lp =0, rp = numbers.length -1;
+    while (lp < rp) {
+      if (numbers[lp] + numbers[rp] == target) {
+        return new int[]{lp + 1, rp + 1};
+      }
+      if (numbers[lp] + numbers[rp] > target) {
+        rp--;
+      }
+      if (numbers[lp] + numbers[rp] < target) {
+        lp++;
+      }
+    }
+    return null;
+  }
+}
+
+```
+
+## 困難點
+
+1. 要想出左右指標移動的條件
+
+## Solve Point
+
+- [x]  初始化 lp = 0, rp = len(numbers) - 1
+- [x]  當 lp < rp 時 做以下運算
+- [x]  當 numbers[lp] + numbers[rp] == target 則回傳 [lp+1, rp+1]
+- [x]  當 numbers[lp] + numbers[rp] > target 則更新 rp -= 1
+- [x]  當 numbers[lp] + numbers[rp] < target 則更新 lp += 1
+- [x]  當跑到 lp = rp  時 , 回傳 nil 代表沒有找到符合的 pair

.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