Merge pull request #20 from dvir019/main

Add sorting algorithms in Java

Author: awaissaddiqui

Sorting/Java/CountingSort.java

@@ -0,0 +1,29 @@
+import java.util.Arrays;
+
+public class CountingSort {
+    public static void bucketSort(int[] arr, int low, int high) {
+        int[] hist = new int[high - low + 1];
+
+        for (int num : arr) {
+            hist[num - low]++;
+        }
+
+        int index = 0;
+
+        for (int i = 0; i < hist.length; i++) {
+            for (int j = 0; j < hist[i]; j++) {
+                arr[index++] = i + low;
+            }
+        }
+    }
+
+    public static void main(String[] args) {
+        int[] arr = {1, 1, 5, 2, 2, 3, 0, 0, -1, 2};
+
+        System.out.println("Unsorted array: " + Arrays.toString(arr));
+
+        bucketSort(arr, -1, 5);
+
+        System.out.println("Sorted array: " + Arrays.toString(arr));
+    }
+}

Sorting/Java/MergeSort.java

@@ -0,0 +1,67 @@
+import java.util.Arrays;
+
+class MergeSort {
+    private static void merge(int[] arr, int left, int middle, int right) {
+        int n1 = middle - left + 1;
+        int n2 = right - middle;
+
+        int[] leftArray = new int[n1];
+        int[] rightArray = new int[n2];
+
+        System.arraycopy(arr, left, leftArray, 0, n1);
+        for (int j = 0; j < n2; j++) {
+            rightArray[j] = arr[middle + 1 + j];
+        }
+
+        int i = 0, j = 0;
+
+        int k = left;
+        while (i < n1 && j < n2) {
+            if (leftArray[i] <= rightArray[j]) {
+                arr[k] = leftArray[i];
+                i++;
+            } else {
+                arr[k] = rightArray[j];
+                j++;
+            }
+            k++;
+        }
+
+        while (i < n1) {
+            arr[k] = leftArray[i];
+            i++;
+            k++;
+        }
+
+        while (j < n2) {
+            arr[k] = rightArray[j];
+            j++;
+            k++;
+        }
+    }
+
+    private static void mergeSort(int[] arr, int left, int right) {
+        if (left < right) {
+            int middle = (left + right) / 2;
+
+            mergeSort(arr, left, middle);
+            mergeSort(arr, middle + 1, right);
+
+            merge(arr, left, middle, right);
+        }
+    }
+
+    private static void mergeSort(int[] arr) {
+        mergeSort(arr, 0, arr.length - 1);
+    }
+
+    public static void main(String[] args) {
+        int[] arr = { 1, 5, 0, -8, 2, 1, 0, -2};
+
+        System.out.println("Unsorted array: " + Arrays.toString(arr));
+
+        mergeSort(arr);
+
+        System.out.println("Sorted array: " + Arrays.toString(arr));
+    }
+}