Non recursive binary search added

Author: rampatra

src/main/java/com/rampatra/arrays/searching/BinarySearch.java

@@ -13,11 +13,11 @@ public class BinarySearch {
      * and returns its index in O(log n) time. The Index may not
      * correspond to the first occurrence of the element.
      *
-     * @param a
-     * @param n
-     * @return
+     * @param a sorted array to be searched
+     * @param n number to be searched in the array
+     * @return index of {@param n} or {@code -1} if not present
      */
-    public static int binarySearch(int[] a, int n) {
+    private static int binarySearch(int[] a, int n) {
         return binarySearch(a, n, 0, a.length - 1);
     }
 
@@ -38,6 +38,28 @@ public static int binarySearch(int[] a, int n, int low, int high) {
         }
     }
 
+    /**
+     * Non-recursive version of binary search.
+     *
+     * @param a sorted array to be searched
+     * @param n number to be searched in the array
+     * @return index of {@param n} or {@code -1} if not present
+     */
+    private static int binarySearchNonRecursive(int[] a, int n) {
+        int low = 0, high = a.length, mid;
+        while (low <= high) {
+            mid = (low + high) / 2;
+            if (n == a[mid]) {
+                return mid;
+            } else if (n < a[mid]) {
+                high = mid - 1;
+            } else {
+                low = mid + 1;
+            }
+        }
+        return -1;
+    }
+
     /**
      * Driver for testing.
      *
@@ -49,5 +71,11 @@ public static void main(String[] a) {
         System.out.println(binarySearch(new int[]{0, 1, 2, 3}, 3));
         System.out.println(binarySearch(new int[]{0, 2}, 0));
         System.out.println(binarySearch(new int[]{0, 1, 2, 2, 2, 3, 3}, 2)); // doesn't return index of first occurrence
+        System.out.println("---------");
+        System.out.println(binarySearchNonRecursive(new int[]{0, 2}, 2));
+        System.out.println(binarySearchNonRecursive(new int[]{0, 1, 2, 3}, 2));
+        System.out.println(binarySearchNonRecursive(new int[]{0, 1, 2, 3}, 3));
+        System.out.println(binarySearchNonRecursive(new int[]{0, 2}, 0));
+        System.out.println(binarySearchNonRecursive(new int[]{0, 1, 2, 2, 2, 3, 3}, 2));
     }
 }