chore(Java) : add ternery search (#850)

* Add Ternery-search in java

* Updated Ternery Search

Added Time compleities and iterative method of the ternery search.

* Updated Ternery-Search

* Updated Ternery Search

Updated Again.

algorithms/Java/README.md

@@ -54,6 +54,7 @@
 - [Allocate minimum number of pages](searching/allocate-min-pages.java)
 - [Exponential Search](searching/Exponential-search.java)
 - [Interpolation Search](searching/interpolation-search.java)
+- [Ternery Search](searching/ternery-search.java)
 
 ## Sorting
 

algorithms/Java/searching/ternery-search.java

@@ -0,0 +1,142 @@
+// Java program to illustrate
+// the iterative approach to ternary search
+// 
+  
+class main {
+  
+    // Function to perform Ternary Search
+    // recursive Function
+    // Time Complexity: O(log3n)
+    // Auxiliary Space: O(log3n)
+  
+    static int ternarySearchRecursive(int l, int r, int key, int ar[])
+  
+    {
+        while (r >= l) {
+  
+            // Find the mid1  mid2
+            int mid1 = l + (r - l) / 3;
+            int mid2 = r - (r - l) / 3;
+  
+            // Check if key is present at any mid
+            if (ar[mid1] == key) {
+                return mid1;
+            }
+            if (ar[mid2] == key) {
+                return mid2;
+            }
+  
+            // Since key is not present at mid,
+            // check in which region it is present
+            // then repeat the Search operation
+            // in that region
+  
+            if (key < ar[mid1]) {
+  
+                // The key lies in between l and mid1
+                r = mid1 - 1;
+            }
+            else if (key > ar[mid2]) {
+  
+                // The key lies in between mid2 and r
+                l = mid2 + 1;
+            }
+            else {
+  
+                // The key lies in between mid1 and mid2
+                l = mid1 + 1;
+                r = mid2 - 1;
+            }
+        }
+  
+        // Key not found
+        return -1;
+    }
+  
+     // Function to perform Iterative Ternary Search
+     // Time Complexity: O(log3n), where n is the size of the array.
+     // Auxiliary Space: O(1)
+  
+    static int ternarySearchIterative(int l, int r, int key, int ar[])
+  
+    {
+        while (r >= l) {
+  
+            // Find the mid1  mid2
+            int mid1 = l + (r - l) / 3;
+            int mid2 = r - (r - l) / 3;
+  
+            // Check if key is present at any mid
+            if (ar[mid1] == key) {
+                return mid1;
+            }
+            if (ar[mid2] == key) {
+                return mid2;
+            }
+  
+            // Since key is not present at mid,
+            // check in which region it is present
+            // then repeat the Search operation
+            // in that region
+  
+            if (key < ar[mid1]) {
+  
+                // The key lies in between l and mid1
+                r = mid1 - 1;
+            }
+            else if (key > ar[mid2]) {
+  
+                // The key lies in between mid2 and r
+                l = mid2 + 1;
+            }
+            else {
+  
+                // The key lies in between mid1 and mid2
+                l = mid1 + 1;
+                r = mid2 - 1;
+            }
+        }
+  
+        // Key not found
+        return -1;
+    }
+  
+  
+    // Driver code
+    public static void main(String args[])
+    {
+        int l, r, p, key;
+  
+        // Get the array
+        // Sort the array if not sorted
+        int ar[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
+  
+        // Starting index
+        l = 0;
+  
+        // length of array
+        r = 9;
+  
+        // Checking for 5
+  
+        // Key to be searched in the array
+        key = 5;
+  
+        // Search the key using ternarySearch
+        p = ternarySearchRecursive(l, r, key, ar);
+  
+        // Print the result
+        System.out.println("Index of " + key + " is " + p);
+  
+        // Checking for 50
+  
+        // Key to be searched in the array
+        key = 50;
+  
+        // Search the key using ternarySearch
+        p = ternarySearchIterative(l, r, key, ar);
+  
+        // Print the result
+        System.out.println("Index of " + key + " is " + p);
+    }
+}