completed all challenges

challenge1/Question1.java

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+package challenge1;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class Question1 {
+
+    private static void findPairs(int[] testArray, int targetSum) {
+        // ASSUMPTIONS:
+        // 1. values in testArray range from 1 - (targetSum - 1)
+
+
+        // The first attempt I made involved nested loops.
+        // I suspected it would be faster to use a dictionary of some kind so I researched
+        // the question and found out
+        // 1. it is
+        // 2. the Java name for a dict is a map
+
+        HashMap<Integer, Integer> pairMap = new HashMap<>();
+
+        // variable used to handle values that are half of targetSum
+        int duplicate = 0;
+
+        for (int i : testArray) {
+            // count number of values that are exactly half of targetSum
+            if (i == targetSum - i) { duplicate++; }
+
+            // every possible pair is added to map
+            pairMap.put(i, targetSum - i);
+        }
+
+        for (int i = 0; i < targetSum; i++) {
+            // removes duplicates from map as well as pairs that don't exist
+            // ex: { 5 } will not print out (5, 1) since 1 is not in array
+
+            // half of targetSum is dealt with later
+            if (pairMap.containsValue(i) && pairMap.containsKey(i) && i != targetSum - i) {
+                pairMap.remove(i);
+            }
+        }
+
+        // remove half of targetSum from map if there isn't more than one in array
+        if (duplicate < 2) {
+            pairMap.remove(targetSum / 2);
+        }
+
+        for (Map.Entry<Integer, Integer> i : pairMap.entrySet()) {
+            System.out.println("(" + i.getKey() + ", " + i.getValue() + ")");
+
+        }
+
+    }
+
+    public static void main(String[] args) {
+        int[] testArray = {2, 4, 5, 1, 3, 5, 4};
+        int targetSum = 6;
+
+        findPairs(testArray, targetSum);
+    }
+}

challenge1/Question2.java

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+package challenge1;
+
+public class Question2 {
+    static boolean isPalindrome(String testString) {
+        String reverse = "";
+
+        for (int i = 0; i < testString.length(); i++){
+            char c = testString.charAt(i);
+            reverse = c + reverse;
+        }
+
+        if (testString.equals(reverse)) { return true; }
+        else { return false; }
+    }
+
+    public static void main(String[] args) {
+        String testString = "bob";
+        String testString2 = "jeff";
+        System.out.println(isPalindrome(testString));
+        System.out.println(isPalindrome(testString2));
+    }
+}

challenge2/.gitignore

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+*.iml
+.gradle
+/local.properties
+/.idea/caches
+/.idea/libraries
+/.idea/modules.xml
+/.idea/workspace.xml
+/.idea/navEditor.xml
+/.idea/assetWizardSettings.xml
+.DS_Store
+/build
+/captures
+.externalNativeBuild

challenge2/app/.gitignore

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+/build

challenge2/app/build.gradle

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+apply plugin: 'com.android.application'
+
+android {
+    compileSdkVersion 28
+    defaultConfig {
+        applicationId "com.example.assignment"
+        minSdkVersion 15
+        targetSdkVersion 28
+        versionCode 1
+        versionName "1.0"
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+    }
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
+        }
+    }
+}
+
+dependencies {
+    implementation fileTree(dir: 'libs', include: ['*.jar'])
+    implementation 'androidx.appcompat:appcompat:1.0.2'
+    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
+    testImplementation 'junit:junit:4.12'
+    androidTestImplementation 'androidx.test:runner:1.1.1'
+    androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.1'
+}

challenge2/app/proguard-rules.pro

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+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile

challenge2/app/src/androidTest/java/com/example/assignment/ExampleInstrumentedTest.java

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+package com.example.assignment;
+
+import android.content.Context;
+
+import androidx.test.InstrumentationRegistry;
+import androidx.test.runner.AndroidJUnit4;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import static org.junit.Assert.*;
+
+/**
+ * Instrumented test, which will execute on an Android device.
+ *
+ * @see <a href="http://d.android.com/tools/testing">Testing documentation</a>
+ */
+@RunWith(AndroidJUnit4.class)
+public class ExampleInstrumentedTest {
+    @Test
+    public void useAppContext() {
+        // Context of the app under test.
+        Context appContext = InstrumentationRegistry.getTargetContext();
+
+        assertEquals("com.example.assignment", appContext.getPackageName());
+    }
+}

challenge2/app/src/main/AndroidManifest.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.example.assignment">
+
+    <application
+        android:allowBackup="true"
+        android:icon="@mipmap/ic_launcher"
+        android:label="@string/app_name"
+        android:roundIcon="@mipmap/ic_launcher_round"
+        android:supportsRtl="true"
+        android:theme="@style/AppTheme">
+        <activity android:name=".MainActivity">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+        <activity android:name=".SingleImageActivity">
+
+        </activity>
+    </application>
+
+</manifest>

challenge2/app/src/main/java/com/example/assignment/ImageAdapter.java

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+package com.example.assignment;
+
+import android.content.Context;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.BaseAdapter;
+import android.widget.ImageView;
+import android.widget.TextView;
+
+
+public class ImageAdapter extends BaseAdapter {
+
+    Context context;
+    String[] title;
+    int[] file;
+    LayoutInflater inflater;
+
+    TextView txtTitle;
+    ImageView imgFile;
+
+    public ImageAdapter(Context context, String[] title, int[] file){
+        this.context = context;
+        this.file = file;
+        this.title = title;
+    }
+
+    @Override
+    public int getCount() {
+        return title.length;
+    }
+
+    @Override
+    public Object getItem(int position) {
+        return null;
+    }
+
+    @Override
+    public long getItemId(int position) {
+        return 1;
+    }
+
+    @Override
+    public View getView(int position, View convertView, ViewGroup parent) {
+
+        inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
+        View itemView = inflater.inflate(R.layout.image, parent, false);
+
+        imgFile = (ImageView) itemView.findViewById(R.id.file);
+        txtTitle = (TextView) itemView.findViewById(R.id.title);
+
+        imgFile.setImageResource(file[position]);
+        txtTitle.setText(title[position]);
+
+        return itemView;
+    }
+
+}

challenge2/app/src/main/java/com/example/assignment/MainActivity.java

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+package com.example.assignment;
+
+import androidx.appcompat.app.AppCompatActivity;
+
+import android.content.Intent;
+import android.os.Bundle;
+import android.view.View;
+import android.widget.AdapterView;
+import android.widget.ListView;
+
+
+public class MainActivity extends AppCompatActivity {
+
+    private ListView list;
+    private ImageAdapter adapter;
+
+    // declare data
+    String[] titles = new String[]{
+            "Monet", "Monet", "Monet", "Van Gogh", "Van Gogh"
+    };
+
+    int[] files = new int[]{
+            R.drawable.img1, R.drawable.img2, R.drawable.img3, R.drawable.img4, R.drawable.img5,
+    };
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+
+        // declare layout file
+        setContentView(R.layout.activity_main);
+
+        // use ListView from activity_main
+        list = (ListView) findViewById(R.id.list);
+
+        adapter = new ImageAdapter(this, titles, files);
+        list.setAdapter(adapter);
+
+        // when an image is pressed, it is displayed
+        list.setOnItemClickListener(new AdapterView.OnItemClickListener() {
+
+            @Override
+            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
+                Intent i = new Intent(MainActivity.this, SingleImageActivity.class);
+                //Putting required data in intent
+                i.putExtra("position", position);
+                i.putExtra("file", files);
+                i.putExtra("title", titles);
+                startActivity(i);
+            }
+        });
+    }
+}