fibonacci_search

Author: shashankchakrawarty98

Arrays-searching/src/fibonacci_search/Fibonacci_Search.py

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+#Made by SHASHANK CHAKRAWARTY
+# Python3 program for Fibonacci search.
+'''
+Works for sorted arrays
+A Divide and Conquer Algorithm.
+Has Log n time complexity.
+
+1)Fibonacci Search divides given array in unequal parts
+
+'''
+
+#Given a sorted array arr[] of size n and an element x to be searched in it. Return index of x if it is present in array else return -1.
+
+
+
+from bisect import bisect_left
+ 
+def fibMonaccianSearch(arr, x, n):
+     
+    # Initialize fibonacci numbers 
+   
+    var2 = 0 # (m-2)'th Fibonacci No.
+    var1 = 1 # (m-1)'th Fibonacci No.
+    res = var2 + var1 # m'th Fibonacci
+
+   
+    # fibM is going to store the smallest 
+    # Fibonacci Number greater than or equal to n 
+    
+    while (res < n):
+        var2 = var1
+        var1 = res
+        res = var2 + var1
+ 
+    # Marks the eliminated range from front
+    offset = -1;
+ 
+    # while there are elements to be inspected.
+    # Note that we compare arr[var2] with x.
+    # When fibM becomes 1, var2 becomes 0 
+   
+
+    while (res > 1):
+         
+        # Check if var2 is a valid location
+        i = min(offset+var2, n-1)
+ 
+        # If x is greater than the value at 
+        # index var2, cut the subarray array 
+        # from offset to i 
+        if (arr[i] < x):
+            res = var1
+            var1 = var2
+            var2 = res - var1
+            offset = i
+ 
+         # If x is greater than the value at 
+        # index var2, cut the subarray 
+        # after i+1
+        elif (arr[i] > x):
+            res = var2
+            var1 = var1 - var2
+            var2 = res - var1
+ 
+        # element found. return index 
+        else :
+            return i
+ 
+    # comparing the last element with x */
+    if(var1 and arr[offset+1] == x):
+        return offset+1;
+ 
+    # element not found. return -1 
+    return -1
+ 
+# Driver Code, you can change the values accordingly
+arr = [10, 22, 35, 40, 45, 50,
+       80, 82, 85, 90, 100]
+n = len(arr)
+x = 85
+print("Found at index:",
+      fibMonaccianSearch(arr, x, n))
+