Updated the code and increased time complexity FibUpdate.cpp

FibUpdate.cpp

@@ -4,38 +4,43 @@
 
 constexpr std::size_t NOT_FOUND = static_cast<std::size_t>(-1);
 
-std::size_t fibonacciSearch(const std::vector<int>& arr, int x) {
-    std::size_t fibM2 = 0; // Two elements before current Fibonacci number
-    std::size_t fibM1 = 1; // One element before current Fibonacci number
-    std::size_t fibM = fibM2 + fibM1; // Current Fibonacci number
-
-    // Find the smallest Fibonacci number greater than or equal to the array size
-    while (fibM < arr.size()) {
+// Function to calculate Fibonacci numbers
+std::size_t calculateFibonacci(std::size_t n) {
+    if (n <= 1) return n;
+    std::size_t fibM2 = 0;
+    std::size_t fibM1 = 1;
+    std::size_t fibM = fibM2 + fibM1;
+    for (std::size_t i = 2; i <= n; ++i) {
+        fibM = fibM1 + fibM2;
         fibM2 = fibM1;
         fibM1 = fibM;
-        fibM = fibM2 + fibM1;
     }
+    return fibM;
+}
+
+std::size_t fibonacciSearch(const std::vector<int>& arr, int x) {
+    std::size_t fibM = 0;
+    std::size_t offset = NOT_FOUND;
 
-    std::size_t offset = NOT_FOUND; // Initialize offset with NOT_FOUND
+    // Find the smallest Fibonacci number greater than or equal to the array size
+    while (calculateFibonacci(fibM) < arr.size()) {
+        fibM++;
+    }
 
-    while (fibM > 1) {
-        std::size_t i = std::min(offset + fibM2, arr.size() - 1);
+    while (fibM > 0) {
+        std::size_t i = std::min(offset + calculateFibonacci(fibM - 2), arr.size() - 1);
 
         if (arr[i] < x) {
-            fibM = fibM1;
-            fibM1 = fibM2;
-            fibM2 = fibM - fibM1;
+            fibM--;
             offset = i;
         } else if (arr[i] > x) {
-            fibM = fibM2;
-            fibM1 = fibM1 - fibM2;
-            fibM2 = fibM - fibM1;
+            fibM -= 2;
         } else {
             return i;
         }
     }
 
-    if (fibM1 && arr[offset + 1] == x)
+    if (offset < arr.size() - 1 && arr[offset + 1] == x)
         return offset + 1;
 
     return NOT_FOUND;
@@ -44,6 +49,12 @@ std::size_t fibonacciSearch(const std::vector<int>& arr, int x) {
 int main() {
     std::vector<int> arr = {10, 22, 35, 40, 45, 50, 80, 82, 85, 90, 100, 235};
     int x = 235;
+
+    if (!std::is_sorted(arr.begin(), arr.end())) {
+        std::cout << "Array must be sorted for Fibonacci search to work." << std::endl;
+        return 1;
+    }
+
     std::size_t ind = fibonacciSearch(arr, x);
 
     if (ind != NOT_FOUND)