Refactored a few searching algorithms

Added documentation to these algorithms

Searches/BinarySearch.java

@@ -1,71 +0,0 @@
-import java.util.Scanner;
-
-/**
- *
- * @author Varun Upadhyay (https://github.com/varunu28)
- *
- */
-
-class BinarySearch
-{
-    /**
-     * This method implements the Generic Binary Search
-     *
-     * @param array The array to make the binary search
-     * @param key The number you are looking for
-     * @param lb The lower bound
-     * @param ub The  upper bound
-     * @return the location of the key
-     **/
-
-    public static <T extends Comparable<T>> int BS(T array[], T key, int lb, int ub)
-    {
-        if ( lb > ub)
-            return -1;
-
-        int mid = (ub+lb) >>> 1;
-        int comp = key.compareTo(array[mid]);
-
-        if (comp < 0)
-            return (BS(array, key, lb, mid-1));
-
-        if (comp > 0)
-            return (BS(array, key, mid + 1, ub));
-
-        return mid;
-    }
-
-    // Driver Program
-    public static void main(String[] args)
-    {
-        Scanner input=new Scanner(System.in);
-
-        // For INTEGER Input
-        Integer[] array = new Integer[10];
-        int key = 5;
-
-        for (int i = 0; i < 10 ; i++ )
-            array[i] = i+1;
-
-        int index = BS(array, key, 0, 9);
-
-        if (index != -1)
-            System.out.println("Number " +  key + " found at index number : " + index);
-        else
-            System.out.println("Not found");
-
-
-        // For STRING Input
-        String[] array1 = {"a", "b", "c", "d", "e"};
-        String key1 = "d";
-
-        int index1 = BS(array1, key1, 0, array1.length-1);
-
-        if (index1 != -1)
-            System.out.println("String " + key1 + " found at index number : " + index1);
-        else
-            System.out.println("Not found");
-
-        input.close();
-    }
-}

Searches/LinearSearch.java

@@ -1,77 +0,0 @@
-import java.io.BufferedReader;
-import java.io.InputStreamReader;
-
-/**
- *
- * @author Varun Upadhyay (https://github.com/varunu28)
- *
- */
-
-public class LinearSearch{
-    /**
-     * The main method
-     * @param args Command line arguments
-     */
-    public static void main(String[] args) throws Exception {
-
-        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
-
-        // Test for Integer inputs
-        Integer[] myArray;
-        int size = 0;
-
-        //Prompt user to create array and its elements
-        System.out.print("Enter the array size: ");
-        size = Integer.parseInt(br.readLine());
-        myArray = new Integer[size];
-        for (int i = 0; i < size; i++){
-            System.out.print("For index " + i + ", enter an integer: ");
-            myArray[i] = Integer.parseInt(br.readLine());
-        }
-
-        //Prompt user to search for particular element
-        System.out.print("Enter integer to search for: ");
-        Integer key = Integer.parseInt(br.readLine());
-
-        //Output array and index of target element, if found
-        System.out.printf("The integer %d is found in index %d\n", key, linearSearch(myArray, key));
-
-        // Test for String inputs
-        String[] myArray1;
-        int size1 = 0;
-
-        //Prompt user to create array and its elements
-        System.out.print("Enter the array size: ");
-        size1 = Integer.parseInt(br.readLine());
-        myArray1 = new String[size];
-        for (int i = 0; i < size1; i++){
-            System.out.print("For index " + i + ", enter a String: ");
-            myArray1[i] = br.readLine();
-        }
-
-        //Prompt user to search for particular element
-        System.out.print("Enter String to search for: ");
-        String key1 = br.readLine();
-
-        //Output array and index of target element, if found
-        System.out.printf("The string %s is found in index %d\n", key1, linearSearch(myArray1, key1));
-    }
-
-    /**
-     * Generic Linear search method
-     *
-     * @param array List to be searched
-     * @param value Key being searched for
-     * @return Location of the key
-     */
-    public static <T extends Comparable<T>> int linearSearch(T[] array, T value) {
-        int lo = 0;
-        int hi = array.length - 1;
-        for (int i = lo; i <= hi; i++) {
-            if (array[i].compareTo(value) == 0) {
-                return i;
-            }
-        }
-        return -1;
-    }
-}

Searches/src/search/BinarySearch.java

@@ -0,0 +1,87 @@
+package search;
+
+import java.util.Random;
+import java.util.stream.Stream;
+
+/**
+ *
+ *
+ *
+ * Binary search is one of the most popular algorithms
+ * The algorithm finds the position of a target value within a sorted array
+ *
+ * Worst-case performance	O(log n)
+ * Best-case performance	O(1)
+ * Average performance	O(log n)
+ * Worst-case space complexity	O(1)
+ *
+ *
+ * @author Varun Upadhyay (https://github.com/varunu28)
+ * @author Podshivalov Nikita (https://github.com/nikitap492)
+ *
+ * @see SearchAlgorithm
+ * @see IterativeBinarySearch
+ *
+ */
+
+class BinarySearch implements SearchAlgorithm {
+
+    /**
+     *
+     * @param array is an array where the element should be found
+     * @param key is an element which should be found
+     * @param <T> is any comparable type
+     * @return index of the element
+     */
+    @Override
+    public  <T extends Comparable<T>> int find(T array[], T key) {
+        return search(array, key, 0, array.length);
+    }
+
+    /**
+     * This method implements the Generic Binary Search
+     *
+     * @param array The array to make the binary search
+     * @param key The number you are looking for
+     * @param left The lower bound
+     * @param right The  upper bound
+     * @return the location of the key
+     **/
+    private <T extends Comparable<T>> int search(T array[], T key, int left, int right){
+        if (right < left) return -1; // this means that the key not found
+
+        // find median
+        int median = (left + right) >>> 1;
+        int comp = key.compareTo(array[median]);
+
+        if (comp < 0) {
+            return search(array, key, left, median - 1);
+        }
+
+        if (comp > 0) {
+            return search(array, key, median + 1, right);
+        }
+
+        return median;
+    }
+
+    // Driver Program
+    public static void main(String[] args) {
+
+        //just generate data
+        Random r = new Random();
+        int size = 200;
+        int maxElement = 100;
+        Integer[] integers = Stream.generate(() -> r.nextInt(maxElement)).limit(size).sorted().toArray(Integer[]::new);
+
+
+        //the element that should be found
+        Integer shouldBeFound = integers[r.nextInt(size - 1)];
+
+        BinarySearch search = new BinarySearch();
+        int atIndex = search.find(integers, shouldBeFound);
+
+        System.out.println(String.format("Should be found: %d. Found %d at index %d. An array length %d"
+                , shouldBeFound, integers[atIndex], atIndex, size));
+    }
+}

Searches/src/search/IterativeBinarySearch.java

@@ -1,14 +1,28 @@
+package search;
 
 import java.util.Arrays;
 import java.util.Random;
 
 /**
- * 
+ * Binary search is one of the most popular algorithms
+ * This class represents iterative version  {@link BinarySearch}
+ * Iterative binary search is likely to have lower constant factors because it doesn't involve the overhead of manipulating the call stack.
+ * But in java the recursive version can be optimized by the compiler to this version.
+ *
+ * Worst-case performance	O(log n)
+ * Best-case performance	O(1)
+ * Average performance	O(log n)
+ * Worst-case space complexity	O(1)
+ *
  * @author Gabriele La Greca : https://github.com/thegabriele97
- * 
+ * @author Podshivalov Nikita (https://github.com/nikitap492)
+ *
+ * @see SearchAlgorithm
+ * @see BinarySearch
+ *
  */
 
-public final class IterativeBinarySearch {
+public final class IterativeBinarySearch implements SearchAlgorithm {
 
     /**
      * This method implements an iterative version of binary search algorithm
@@ -18,13 +32,14 @@ public final class IterativeBinarySearch {
      * 
      * @return the index of key in the array or -1 if not found
      */
-    public static <T extends Comparable<T>> int binarySearch(T[] array, T key) {
+    @Override
+    public  <T extends Comparable<T>> int find(T[] array, T key) {
         int l, r, k, cmp;
 
         l = 0;
-        r = array.length - 1;
+        r = array.length;
 
-        while (l <= r) {
+        while (l < r) {
             k = (l + r) / 2;
             cmp = key.compareTo(array[k]);
 
@@ -32,7 +47,7 @@ public final class IterativeBinarySearch {
                 return k;
             } else if (cmp < 0) {
                 r = --k;
-            } else if (cmp > 0) {
+            } else {
                 l = ++k;
             }
         }
@@ -53,7 +68,7 @@ public final class IterativeBinarySearch {
         //Arrays.sort(array); //if needed
         Integer key = base + rand.nextInt(array.length * 2); //can generate keys that aren't in array
 
-        System.out.println(binarySearch(array, key));
+        System.out.println(new IterativeBinarySearch().find(array, key));
         System.out.println(Arrays.binarySearch(array, key));
     }
 }

Searches/src/search/LinearSearch.java

@@ -0,0 +1,63 @@
+package search;
+
+import java.util.Random;
+import java.util.stream.Stream;
+
+/**
+ * Linear search is the easiest search algorithm
+ * It works with sorted and unsorted arrays (an binary search works only with sorted array)
+ * This algorithm just compares all elements of an array to find a value
+ *
+ * Worst-case performance	O(n)
+ * Best-case performance	O(1)
+ * Average performance	O(n)
+ * Worst-case space complexity
+ *
+ *
+ * @author Varun Upadhyay (https://github.com/varunu28)
+ * @author Podshivalov Nikita (https://github.com/nikitap492)
+ *
+ *
+ * @see BinarySearch
+ * @see SearchAlgorithm
+ */
+
+public class LinearSearch implements SearchAlgorithm {
+
+    /**
+     * Generic Linear search method
+     *
+     * @param array List to be searched
+     * @param value Key being searched for
+     * @return Location of the key
+     */
+    @Override
+    public <T extends Comparable<T>> int find(T[] array, T value) {
+        for (int i = 0; i < array.length ; i++) {
+            if (array[i].compareTo(value) == 0) {
+                return i;
+            }
+        }
+        return -1;
+    }
+
+
+    public static void main(String[] args) {
+        //just generate data
+        Random r = new Random();
+        int size = 200;
+        int maxElement = 100;
+        Integer[] integers = Stream.generate(() -> r.nextInt(maxElement)).limit(size).toArray(Integer[]::new);
+
+
+        //the element that should be found
+        Integer shouldBeFound = integers[r.nextInt(size - 1)];
+
+        LinearSearch search = new LinearSearch();
+        int atIndex = search.find(integers, shouldBeFound);
+
+        System.out.println(String.format("Should be found: %d. Found %d at index %d. An array length %d"
+                , shouldBeFound, integers[atIndex], atIndex, size));
+    }
+
+}

Searches/src/search/SearchAlgorithm.java

@@ -0,0 +1,20 @@
+package search;
+
+/**
+ *  The common interface of most searching algorithms
+ *
+ * @author Podshivalov Nikita (https://github.com/nikitap492)
+ *
+ **/
+public interface SearchAlgorithm {
+
+    /**
+     *
+     * @param key is an element which should be found
+     * @param array is an array where the element should be found
+     * @param <T> Comparable type
+     * @return first found index of the element
+     */
+    <T extends Comparable<T>> int find(T array[], T key);
+
+}