finds last position of search element using binary search in O(logn)

Author: NirmalSilwal

CodingBlocks Training/Day14/lastIndexSearch.java

@@ -0,0 +1,35 @@
+package Lecture14;
+
+public class lastIndexSearch {
+
+	public static void main(String[] args) {
+
+		int[] arr = { 10, 20, 25, 30, 30, 30, 30, 30, 40, 50, 60, 70 };
+		int key = 30;
+		System.out.println(binarySearchLastIndex(arr, key));
+
+	}
+
+	public static int binarySearchLastIndex(int[] arr, int key) {
+
+		int start = 0, end = arr.length - 1;
+		int ans = -1;
+
+		while (start <= end) {
+
+			int mid = (start + end) / 2;
+
+			if (arr[mid] == key) {
+				ans = mid;
+			}
+			if (key >= arr[mid]) {
+				start = mid + 1;
+			} else {
+				end = mid - 1;
+			}
+		}
+
+		return ans;
+	}
+
+}