add some exs

interview_cake/binary_search.py

@@ -1 +0,0 @@
-#!/usr/bin/env python

interview_cake/sort_and_search/binary_search.py

@@ -0,0 +1,48 @@
+#!/usr/bin/env python
+
+
+def binary_search(array, value):   
+    last, first = len(array), 0
+    
+    while first < last:
+        mid = (last - first)//2
+        item = array[mid]
+        
+        if item == value:
+            return True
+        
+        elif item < value:
+            last = mid
+        
+        else:
+            first = mid 
+    
+    return False
+
+def binary_search_rec(array, value, first=0, last=None):
+    last = last or len(array)
+    if len(array[first:last]) < 1:
+        return False
+    
+    mid = (last - first)//2
+    if array[mid] == value:
+        return True
+    elif array[mid] < value:
+        return binary_search_rec(array, value, first=first, last=mid)
+    else:
+        return binary_search_rec(array, value, first=mid, last=last)
+
+    
+array = [3, 4, 6, 7, 10, 11, 34, 67, 84]
+value = 6
+assert(binary_search(array, value) == True)   
+assert(binary_search_rec(array, value) == True)  
+value = 8
+assert(binary_search(array, value) == False)
+assert(binary_search_rec(array, value) == False)  
+array = [8]
+assert(binary_search(array, value) == True)
+assert(binary_search_rec(array, value) == True)  
+array = []
+assert(binary_search(array, value) == False)
+assert(binary_search_rec(array, value) == False)  

interview_cake/sort_and_search/merge_sort.py

@@ -0,0 +1,37 @@
+ #!/usr/bin/env python
+
+def merge_sort(list_to_sort):
+    # Base case: lists with fewer than 2 elements are sorted
+    if len(list_to_sort) < 2:
+        return list_to_sort
+
+    # Step 1: divide the list in half
+    mid_index = len(list_to_sort) / 2
+    left  = list_to_sort[:mid_index]
+    right = list_to_sort[mid_index:]
+
+    # Step 2: sort each half
+    sorted_left  = merge_sort(left)
+    sorted_right = merge_sort(right)
+
+    # Step 3: merge the sorted halves
+    sorted_list = []
+    current_index_left = 0
+    current_index_right = 0
+
+    while len(sorted_list) < len(left) + len(right):
+        if ((current_index_left < len(left)) and
+                (current_index_right == len(right) or
+                 sorted_left[current_index_left] < sorted_right[current_index_right])):
+            sorted_list.append(sorted_left[current_index_left])
+            current_index_left += 1
+        else:
+            sorted_list.append(sorted_right[current_index_right])
+            current_index_right += 1
+    return sorted_list
+
+
+
+list_to_sort = [5, 3, 7, 12, 1, 0, 10]
+
+print merge_sort(list_to_sort)