Merge pull request #11 from anthonyc1/java-algo

Implement Linear Search, and Quick Sort

Author: dynamitechetan

LinearSearch.java

@@ -0,0 +1,48 @@
+import java.util.Scanner;
+
+public class LinearSearch{
+	//Main method
+	public static void main(String[] args){
+
+		Scanner input = new Scanner(System.in);
+		int[] myArray;
+		int size = 0;
+
+		//Prompt user to create array and its elements
+		System.out.print("Enter the array size: ");
+		size = input.nextInt();
+		myArray = new int[size];
+		for (int i = 0; i < size; i++){
+			System.out.print("For index " + i + ", enter an integer: ");
+			myArray[i] = input.nextInt();
+		}
+
+		//Prompt user to search for particular element
+		System.out.print("Enter integer to search for: ");
+		int key = input.nextInt();
+
+		//Output array and index of target element, if found
+		printarray(myArray);
+		System.out.printf("The integer %d is found in index %d\n", key, linearsearch(myArray, key));
+
+	}
+
+	//Linear search method
+	public static int linearsearch(int[] list, int key){
+
+		for (int i = 0; i< list.length; i++){
+			if (list[i] == key){
+				return i;
+			}
+				
+		} return -1;	
+	}
+	//Helper method
+	public static void printarray(int[] a){
+		System.out.print("The array is: ");
+		for( int d: a){
+			System.out.print(d+" ");
+		}
+		System.out.println();
+	}
+}

Quicksort.java

@@ -0,0 +1,71 @@
+import java.util.Scanner;
+
+public class Quicksort{
+
+	public static void main(String[] args){
+		Scanner input = new Scanner(System.in);
+		int[] array;
+		int size = 0;
+
+		//Prompt user to create array and its elements
+		System.out.print("Enter the size of the array: ");
+		size = input.nextInt();
+		array = new int[size];
+		for (int i = 0; i < size; i++){
+			System.out.print("For index " + i + ", give an integer input: ");
+			array[i] = input.nextInt();
+		}
+
+		//Output inputted array
+		System.out.println("The array is: ");
+		printarray(array);
+		System.out.println();
+
+		//Run quicksort, and output sorted array
+		quicksort(array, 0, array.length - 1);
+		System.out.println("The sorted array is: ");
+		printarray(array);
+		System.out.println();
+	}
+	
+	//Quicksort Method
+	public static void quicksort(int[] ar, int start, int end){
+		int[] array;
+		
+		int i = start, j = end;
+		if (end-start >= 1){
+			int pivot = ar[end];
+			while (i< j){
+				while (ar[i]<pivot && i<end){
+					i++;
+				}
+				while (ar[j]>=pivot && j>start){
+					j--;
+				}
+				if (i<j){
+					swap(ar, i, j);
+				}
+			} swap(ar, end, i);
+
+			quicksort(ar, start, i-1);
+			quicksort(ar, i+1, end);
+		} else{
+			return;
+		}
+	}
+
+	//Helper methods
+	public static void swap(int[] ar, int index1, int index2){
+
+		int temp = ar[index1];
+		ar[index1] = ar[index2];
+		ar[index2] = temp;
+	}
+
+	public static void printarray(int[] array){
+
+		for (int data : array){
+			System.out.print(data + " ");
+		}
+	}
+}