sync

MergeSort/pom.xml

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.calebfontenot</groupId>
+    <artifactId>MergeSort</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <packaging>jar</packaging>
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <maven.compiler.source>20</maven.compiler.source>
+        <maven.compiler.target>20</maven.compiler.target>
+        <exec.mainClass>com.calebfontenot.mergesort.MergeSort</exec.mainClass>
+    </properties>
+</project>

MergeSort/src/main/java/com/calebfontenot/mergesort/MergeSort.java

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+/*
+ * Click nbfs://nbhost/SystemFileSystem/Templates/Licenses/license-default.txt to change this license
+ */
+package com.calebfontenot.mergesort;
+
+/**
+ *
+ * @author caleb
+ */
+public class MergeSort {
+
+    public static void printArray(int[] array) {
+        for (int i = 0; i < array.length; i++) {
+            System.out.print(array[i] + " ");
+        }
+        System.out.println();
+    }
+
+    public static void main(String args[]) {
+
+        // merge sort = recursively divide array in 2, sort, re-combine
+        // run-time complexity = O(n Log n)
+        // space complexity    = O(n)
+        int[] array = {8, 2, 5, 3, 4, 7, 6, 1, 0};
+        printArray(array);
+        mergeSort(array);
+        printArray(array);
+
+    }
+
+    private static void mergeSort(int[] array) {
+
+        int length = array.length;
+        if (length <= 1) {
+            return; //base case
+        }
+        int middle = length / 2;
+        int[] leftArray = new int[middle];
+        int[] rightArray = new int[length - middle];
+        int i = 0; //left array
+        int j = 0; //right array
+        
+        for (; i < length; i++) {
+            if (i < middle) {
+                leftArray[i] = array[i];
+            } else {
+                rightArray[j] = array[i];
+                j++;
+            }
+        }
+        mergeSort(leftArray);
+        mergeSort(rightArray);
+        merge(leftArray, rightArray, array);
+    }
+
+    private static void merge(int[] leftArray, int[] rightArray, int[] array) {
+
+        int leftSize = array.length / 2;
+        int rightSize = array.length - leftSize;
+        int i = 0, l = 0, r = 0; //indices
+        
+        //check the conditions for merging
+        while (l < leftSize && r < rightSize) {
+            if (leftArray[l] < rightArray[r]) {
+                array[i] = leftArray[l];
+                i++;
+                l++;
+            } else {
+                array[i] = rightArray[r];
+                i++;
+                r++;
+            }
+        }
+        
+        while (l < leftSize) {
+            array[i] = leftArray[l];
+            i++;
+            l++;
+        }
+
+        while (r < rightSize) {
+            array[i] = rightArray[r];
+            i++;
+            r++;
+        }
+    }
+
+}