binary search implementation - O(logn)

Author: NirmalSilwal

CodingBlocks Training/Day14/binarySearch.java

@@ -0,0 +1,35 @@
+package Lecture14;
+
+public class binarySearch {
+
+	public static void main(String[] args) {
+
+		int[] arr = { 10, 20, 30, 40, 50, 60, 70, 80 };
+		int key = 70;
+		int start = 0, end = arr.length - 1;
+		int result = binarySearchElement(arr, key, start, end);
+		if (result >= 0) {
+			System.out.println(result);
+		} else {
+			System.out.println("element not present");
+		}
+	}
+
+	// returns index of searched element if found else return -1
+	public static int binarySearchElement(int[] arr, int key, int start, int end) {
+		if (start == end && key != arr[start]) {
+			return -1;
+		}
+		int mid = (start + end) / 2;
+
+		if (arr[mid] == key) {
+			return mid;
+		} else {
+			if (key > arr[mid]) {
+				return binarySearchElement(arr, key, mid + 1, end);
+			} else {
+				return binarySearchElement(arr, key, start, mid - 1);
+			}
+		}
+	}
+}