Added Ternary Search

Author: ribhav-pahuja

Searches/TernarySearch.java

@@ -0,0 +1,74 @@
+import java.util.Scanner;
+
+public class TernarySearch{
+
+    /**
+     * @param arr The **Sorted** array in which we will search the element.
+     * @param value The value that we want to search for.
+     * @return The index of the element if found.
+     * Else returns -1.
+     */
+    public static int ternarySearch(int[] arr, int value){
+        return ternarySearch(arr, value, 0, arr.length - 1);
+    }
+
+    /**
+     * @param arr The **Sorted** array in which we will search the element.
+     * @param key The value that we want to search for.
+     * @param start The starting index from which we will start Searching.
+     * @param end The ending index till which we will Search.
+     * @return Returns the index of the Element if found.
+     * Else returns -1.
+     */
+    public static int ternarySearch(int[] arr, int key, int start, int end) {
+        if (start > end){
+            return -1;
+        }
+        /* First boundary: add 1/3 of length to start */
+        int mid1 = start + (end - start) / 3;
+        /* Second boundary: add 2/3 of length to start */
+        int mid2 = start + 2 * (end - start) / 3;
+        if (arr[mid1] == key) {
+            return mid1;
+        }
+        else if (arr[mid2] == key) {
+            return mid2;
+        }
+
+        /* Search the first (1/3) rd part of the array.*/
+
+        else if (key < arr[mid1]) {
+            return ternarySearch(arr, key, start, mid1 - 1);
+        }
+        /* Search 3rd (1/3)rd part of the array */
+
+        else if (key > arr[mid2]) {
+            return ternarySearch(arr, key, mid2 + 1, end);
+        }
+        /* Search middle (1/3)rd part of the array */
+
+        else {
+            return ternarySearch(arr, key, mid1, mid2);
+        }
+    }
+
+    public static void main(String[] args) {
+        Scanner s = new Scanner(System.in);
+        System.out.println("Enter number of elements in the array");
+        int n = s.nextInt();
+        int arr[] = new int[n];
+        System.out.println("Enter the elements of the array");
+        for (int i= 0; i < n; i++){
+            arr[i] = s.nextInt();
+        }
+        System.out.println("Enter element to search for : ");
+        int k = s.nextInt();
+        int ans = ternarySearch(arr, k);
+        if (ans == -1) {
+            System.out.println(" The element is not present in the array.");
+        }
+        else {
+            System.out.println("The element is present at the position" + ans);
+        }
+    }
+}