adding bubble sort, quick sort and selection sort

Sorting algorithms/BubbleSort.java

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+import java.util.Scanner;
+/**
+ *
+ * @author BrundaSreedhar
+ */
+public class BubbleSort {
+    void bubbleSort(int array[]) 
+    { 
+        int n = array.length; 
+        for (int i = 0; i < n-1; i++) 
+            for (int j = 0; j < n-i-1; j++) 
+                if (array[j] > array[j+1]) 
+                { 
+                    // swap temp and array[i] 
+                    int temp = array[j]; 
+                    array[j] = array[j+1]; 
+                    array[j+1] = temp; 
+                } 
+    } 
+     public static void main(String args[]) 
+    { 
+        BubbleSort ob = new BubbleSort(); 
+        Scanner sc= new Scanner(System.in);
+
+        System.out.println("Enter number of elements to be sorted: ");
+        int num=sc.nextInt();
+        int array[] = new int[num]; 
+
+        System.out.println("Enter array elements");
+         for(int i=0; i< num; i++){
+             array[i] = sc.nextInt();
+        }
+
+         ob.bubbleSort(array); 
+         System.out.println("Array after bubble sort.."); 
+
+        for(int i=0;i<num;i++){
+            System.out.print(array[i] + " ");  
+        } 
+    } 
+
+}

Sorting algorithms/QuickSort.java

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+
+import java.util.Scanner;
+
+public class QuickSort
+{
+    /* This function takes last element as pivot,
+       places the pivot element at its correct
+       position in sorted array, and places all
+       smaller (smaller than pivot) to left of
+       pivot and all greater elements to right
+       of pivot */
+    private int partition(int arr[], int low, int high)
+    {
+        int pivot = arr[high]; 
+        int i = (low-1); // index of smaller element
+        for (int j=low; j<high; j++)
+        {
+            // If current element is smaller than or
+            // equal to pivot
+            if (arr[j] <= pivot)
+            {
+                i++;
+
+                // swap arr[i] and arr[j]
+                int temp = arr[i];
+                arr[i] = arr[j];
+                arr[j] = temp;
+            }
+        }
+
+        // swap arr[i+1] and arr[high] (or pivot)
+        int temp = arr[i+1];
+        arr[i+1] = arr[high];
+        arr[high] = temp;
+
+        return i+1;
+    }
+
+  /**
+  * 
+  * @param arr
+  * @param low
+  * @param high 
+  */
+
+   void quickSort(int arr[], int low, int high)
+    {
+        if (low < high)
+        {
+            /* pi is partitioning index, arr[pi] is 
+              now at right place */
+            int pi = partition(arr, low, high);
+
+            // Recursively sort elements before
+            // partition and after partition
+            quickSort(arr, low, pi-1);
+            quickSort(arr, pi+1, high);
+        }
+    }
+
+    public static void main(String args[])
+    {
+          Scanner sc= new Scanner(System.in);
+
+        System.out.println("Enter number of elements to be sorted: ");
+        int num=sc.nextInt();
+        int array[] = new int[num]; 
+
+        System.out.println("Enter array elements");
+         for(int i=0; i< num; i++){
+             array[i] = sc.nextInt();
+        }
+        QuickSort ob = new QuickSort();
+        ob.quickSort(array, 0, num-1);
+
+        for(int i=0;i<num;i++){
+            System.out.print(array[i] + " ");  
+        } 
+    }
+}

Sorting algorithms/SelectionSort.java

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+
+import java.util.Scanner;
+
+public class SelectionSort
+{
+	void selectionSort(int arr[])
+	{
+		int n = arr.length;
+
+		// Move the boundary of unsorted subarray one by one
+		for (int i = 0; i < n-1; i++)
+		{
+			// Find the minimum element in unsorted array
+			int min = i;
+			for (int j = i+1; j < n; j++)
+				if (arr[j] < arr[min])
+					min = j;
+
+			// Swap the found minimum element with the first
+			// element
+			int temp = arr[min];
+			arr[min] = arr[i];
+			arr[i] = temp;
+		}
+	}
+public static void main(String args[]) 
+    { 
+        SelectionSort ob = new SelectionSort(); 
+        Scanner sc= new Scanner(System.in);
+
+        System.out.println("Enter number of elements to be sorted: ");
+        int num=sc.nextInt();
+        int array[] = new int[num]; 
+
+        System.out.println("Enter array elements");
+         for(int i=0; i< num; i++){
+             array[i] = sc.nextInt();
+        }
+
+         ob.selectionSort(array); 
+         System.out.println("Array after selection sort.."); 
+
+        for(int i=0;i<num;i++){
+            System.out.print(array[i] + " ");  
+        } 
+    } 
+}