Update BinarySearch.java

binary search explained in a better way using functions

Author: srinjoy07pal

core-java/basics/BinarySearch.java

@@ -1,19 +1,47 @@
-package basics;
-import java.util.Arrays;
-
-public class BinarySearch {
-	
-	public static void main(String[] args) {
-		
-		int arr[] = {10, 20, 15, 22, 35};
-		Arrays.sort(arr);
-		
-		int key = 35;
-		int res = Arrays.binarySearch(arr, key);
-		if(res >= 0){
-			System.out.println(key + " found at index = "+ res);
-		} else {
-			System.out.println(key + " not found");
-		} 
+// Java implementation of iterative Binary Search
+
+import java.io.*;
+
+class BinarySearch {
+
+	// Returns index of x if it is present in arr[].
+	int binarySearch(int arr[], int x)
+	{
+		int l = 0, r = arr.length - 1;
+		while (l <= r) {
+			int m = l + (r - l) / 2;
+
+			// Check if x is present at mid
+			if (arr[m] == x)
+				return m;
+
+			// If x greater, ignore left half
+			if (arr[m] < x)
+				l = m + 1;
+
+			// If x is smaller, ignore right half
+			else
+				r = m - 1;
+		}
+
+		// If we reach here, then element was
+		// not present
+		return -1;
+	}
+
+	// Driver code
+	public static void main(String args[])
+	{
+		BinarySearch ob = new BinarySearch();
+		int arr[] = { 2, 3, 4, 10, 40 };
+		int n = arr.length;
+		int x = 10;
+		int result = ob.binarySearch(arr, x);
+		if (result == -1)
+			System.out.println(
+				"Element is not present in array");
+		else
+			System.out.println("Element is present at "
+							+ "index " + result);
 	}
 }