From 18f8780467f1555471ec8eb08cdd67ff388f4bcd Mon Sep 17 00:00:00 2001
From: mtsagkl <mtsagkl@csd.auth.gr>
Date: Sun, 23 Nov 2025 22:51:08 +0200
Subject: [PATCH 1/3] Add Fibonacci Search implementation

---
 FibonacciSearch.java | 78 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 78 insertions(+)
 create mode 100644 FibonacciSearch.java

diff --git a/FibonacciSearch.java b/FibonacciSearch.java
new file mode 100644
index 00000000..bb7d9680
--- /dev/null
+++ b/FibonacciSearch.java
@@ -0,0 +1,78 @@
+/**
+ * Fibonacci Search Implementation in Java
+ *
+ * This class demonstrates the Fibonacci Search algorithm, an efficient
+ * searching technique for sorted arrays that uses Fibonacci numbers to
+ * divide the search space. The algorithm runs in O(log n) time.
+ *
+ * @author mtsagkl
+ */
+public class FibonacciSearch {
+    /**
+     * Executes the Fibonacci Search algorithm on a sorted array.
+     * This method uses Fibonacci numbers to split the search range .
+     *
+     * @param arr the sorted array in which the search is performed
+     * @param n   the array's size
+     * @param key the element to search for
+     * @return    the index of the key if found, otherwise -1
+     */
+    static int fibonacci_search(int arr[], int n,int key ){
+        int offset =-1;
+        int fm2=0;
+        int fm1=1;
+        int fm=fm1+fm2;
+
+        while(fm<n){
+            fm2=fm1;
+            fm1=fm;
+            fm=fm2+fm1;
+        }
+
+        while (fm>1){
+            int i;
+            if (offset+fm2<n-1){
+                i=offset+fm2;
+            }
+            else
+                i=n-1;
+
+            if(arr[i]<key){
+                fm=fm1;
+                fm1=fm2;
+                fm2=fm-fm1;
+                offset=i;
+            }
+            else if(arr[i]>key){
+                fm=fm2;
+                fm1=fm1-fm2;
+                fm2=fm-fm1;
+            }
+            else 
+                return i;
+        }
+        if (fm1==1 && arr[offset+1]==key)
+            return offset +1;
+        return -1;
+    }
+
+    /**
+     * Main method to demonstrate Fibonacci search functionality
+     */
+    public static void main(String[] args) {
+        int n , key;
+        int arr[]={-15,-5,2,5,7,10,28,30,45,56};
+        System.out.print("Array's elements: ");
+        for (int i=0; i<arr.length; i++){
+            System.out.print(arr[i]+" ");
+        }
+        n = arr.length;
+        key = 10;
+        System.out.print("\nThe element to be searched: " + key);
+        int index = fibonacci_search(arr, n, key);
+        if(index >= 0)
+            System.out.print("\nFound at index " + index);
+        else
+            System.out.print("\nUnsuccessful search");
+    }
+}

From f68d83c70d05c1c8ccbfeb2e56477931438aa1e7 Mon Sep 17 00:00:00 2001
From: mtsagkl <mtsagkl@csd.auth.gr>
Date: Sun, 23 Nov 2025 23:18:39 +0200
Subject: [PATCH 2/3] Add Fibonacci Search implementation

---
 FibonacciSearch.java | 26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/FibonacciSearch.java b/FibonacciSearch.java
index bb7d9680..e8f01ec4 100644
--- a/FibonacciSearch.java
+++ b/FibonacciSearch.java
@@ -23,6 +23,7 @@ static int fibonacci_search(int arr[], int n,int key ){
         int fm1=1;
         int fm=fm1+fm2;
 
+        // find smallest Fibonacci number >= n
         while(fm<n){
             fm2=fm1;
             fm1=fm;
@@ -37,23 +38,27 @@ static int fibonacci_search(int arr[], int n,int key ){
             else
                 i=n-1;
 
+            // if value is smaller, move right
             if(arr[i]<key){
                 fm=fm1;
                 fm1=fm2;
                 fm2=fm-fm1;
                 offset=i;
             }
+            // if value is greater, move left
             else if(arr[i]>key){
                 fm=fm2;
                 fm1=fm1-fm2;
                 fm2=fm-fm1;
             }
-            else 
+            // value found
+            else
                 return i;
         }
+        // check last possible position
         if (fm1==1 && arr[offset+1]==key)
             return offset +1;
-        return -1;
+        return -1;  // not found
     }
 
     /**
@@ -67,12 +72,23 @@ public static void main(String[] args) {
             System.out.print(arr[i]+" ");
         }
         n = arr.length;
+
+        // Test with element in array
         key = 10;
-        System.out.print("\nThe element to be searched: " + key);
+        System.out.println("\nThe element to be searched: " + key);
         int index = fibonacci_search(arr, n, key);
         if(index >= 0)
-            System.out.print("\nFound at index " + index);
+            System.out.println("Found at index " + index);
+        else
+            System.out.println("Not found");
+
+        // Test with element not in array
+        key = 20;
+        System.out.println("The element to be searched: " + key);
+        index = fibonacci_search(arr, n, key);
+        if(index >= 0)
+            System.out.println("Found at index " + index);
         else
-            System.out.print("\nUnsuccessful search");
+            System.out.println("Not found");
     }
 }

From d8bb67a5b1446ca5b053e1149f28ad3ae6a0401d Mon Sep 17 00:00:00 2001
From: mtsagkl <mtsagkl@csd.auth.gr>
Date: Fri, 26 Dec 2025 19:14:21 +0200
Subject: [PATCH 3/3] Add Fibonacci Search implementation

---
 JavaPracticeHacktoberfest.iml                          | 1 +
 FibonacciSearch.java => Searching/FibonacciSearch.java | 0
 2 files changed, 1 insertion(+)
 rename FibonacciSearch.java => Searching/FibonacciSearch.java (100%)

diff --git a/JavaPracticeHacktoberfest.iml b/JavaPracticeHacktoberfest.iml
index 48426fcc..dac32f97 100644
--- a/JavaPracticeHacktoberfest.iml
+++ b/JavaPracticeHacktoberfest.iml
@@ -4,6 +4,7 @@
     <output url="file://$MODULE_DIR$/bin" />
     <exclude-output />
     <content url="file://$MODULE_DIR$" />
+    <orderEntry type="jdk" jdkName="corretto-17" jdkType="JavaSDK" />
     <orderEntry type="sourceFolder" forTests="false" />
   </component>
 </module>
\ No newline at end of file
diff --git a/FibonacciSearch.java b/Searching/FibonacciSearch.java
similarity index 100%
rename from FibonacciSearch.java
rename to Searching/FibonacciSearch.java