Create ternarySearch.java

Java/ternarySearch.java

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+// Java program to illustrate 
+// recursive approach to ternary search 
+
+class GFG { 
+
+	// Function to perform Ternary Search 
+	static int ternarySearch(int l, int r, int key, int ar[]) 
+	{ 
+		if (r >= l) { 
+
+			// Find the mid1 and 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 
+				return ternarySearch(l, mid1 - 1, key, ar); 
+			} 
+			else if (key > ar[mid2]) { 
+
+				// The key lies in between mid2 and r 
+				return ternarySearch(mid2 + 1, r, key, ar); 
+			} 
+			else { 
+
+				// The key lies in between mid1 and mid2 
+				return ternarySearch(mid1 + 1, mid2 - 1, key, ar); 
+			} 
+		} 
+
+		// 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 = ternarySearch(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 = ternarySearch(l, r, key, ar); 
+
+		// Print the result 
+		System.out.println("Index of " + key + " is " + p); 
+	} 
+}