Binary Search

Author: Shikha-code36

Searching-Algo/binarysearch.py

@@ -2,19 +2,42 @@
                                                              Binary Search
  Binary Search is a searching algorithm used in a sorted array by repeatedly dividing the search interval in half.
 '''
-
-def binarysearch(list,target):
-    left=0
-    right=len(list)-1
+# iterative approach
+def binarysearch(list, target):
+    left = 0
+    right = len(list)-1
     while left <= right:
         mid = (left+right)//2
         if target == list[mid]:
             return mid
-        elif target> list[mid]:
-            left=mid+1
+        elif target > list[mid]:
+            left = mid+1
         else:
-            right=mid-1
-            
+            right = mid-1
+
     return -1
 
-print(binarysearch([2,3,4,5],5)) #3
+
+print(binarysearch([2, 3, 4, 5], 5))  # 3
+
+# recursive approach
+def binarysearch(list, left, right, target):
+    if right >= left:
+        mid = (left+right)//2
+
+        if target == list[mid]:
+            return mid
+        # If element is smaller than mid, then it can only
+        # be present in left subarray
+        elif list[mid] > target:
+            return binarysearch(list, left, mid-1, target)
+        # Else the element can only be present in right subarray
+        else:
+            return binarysearch(list, mid+1, right, target)
+    else:
+        return -1
+
+
+list = [2, 3, 4, 10, 11, 16, 90, 32, 7]
+target = 16
+print(binarysearch(list, 0, len(list)-1, target))  # 5