add binary search

Author: Muh. Angga Muttaqien

searching/binary-search.py

@@ -0,0 +1,55 @@
+
+def binary_search(sorted_collection, item):
+
+    left = 0
+    right = len(sorted_collection) -1
+
+    while left <= right:
+        midpoint = (left + right) // 2
+        current_item = sorted_collection[midpoint]
+        if current_item == item:
+            return midpoint
+        else:
+            if item < current_item:
+                right = midpoint - 1
+            else:
+                left = midpoint + 1
+    
+    return None
+
+
+def __assert_sorted(collection):
+
+    if collection != sorted(collection):
+        raise ValueError('Collection must be sorted')
+
+    return True
+
+
+def main():
+    print("=== Binary Search (Algorithm) - A half-interval search, logarithmic search, or binary search that finds the position of a target value within a sorted array. Binary search compares the target value to the middle element of the array")
+    
+    import sys
+
+    user_input = raw_input("Enter numbers separated by a comma: ")
+    collection = [int(item) for item in user_input.split(',')]
+
+    try:
+        __assert_sorted(collection)
+    except ValueError:
+        sys.exit('Sequence must be sorted to apply binary search')
+
+
+    target_input = input("Enter single number to be found in the list: ")
+    target = int(target_input)
+
+    result = binary_search(collection, target)
+
+    if result is not None:
+        print("{} found at position: {}".format(target, result))
+    else:
+        print("Not found")
+
+
+if __name__=='__main__':
+	main()