recursion exercises

Author: Blooverh

PythonDataStructsAndAlgo/Notes.md

@@ -41,3 +41,9 @@
 > To design a good algorithm, it is useful to think of the different ways we might define the subproblems that have the same general structure as the original problem.
 
 >Tail recursion - if any recursive call that is made from one context is the very last operation in that context, with the return value of the recursive call immediately returned by enclosing recursion.
+
+# Array-Base Sequences
+> list, tuple and str classes have in common the support of indexing to access individual elements of a sequence, and each uses a low-level concept known as an array to represent that sequence.
+
+> * *Shallow copy* - an array copy of another array that references the same elements as in the first list.
+> * With 

PythonDataStructsAndAlgo/Recursion/C-4-12.py

@@ -0,0 +1,30 @@
+"""Recursive algorithm to find the product of 2 integers m and n using only addition and subtraction"""
+def productRecursion(n, m):
+    total=0
+    if m ==0 or n==0:
+        return 0
+    elif m >0 and n>0 :
+        for _ in range(m):
+            total+=n
+    elif (m >0 and n<0):
+        if n%2==0:
+            for _ in range(m):
+                total+=abs(n)
+        else:
+            total+=n
+    elif n>0 and m<0:
+        if m%2==0:
+            for _ in range(n):
+                total+=m
+        else:
+            total+=m
+    elif n<0 and m<0:
+        for _ in range(abs(m)):
+                total+=abs(n)
+    return total
+
+print(productRecursion(4,3)) #correct
+print(productRecursion(3,0)) #correct
+print(productRecursion(-4,-3))#correct
+print(productRecursion(3,-4))
+print(productRecursion(-2,2))#correct

PythonDataStructsAndAlgo/Recursion/C-4-15.py

@@ -0,0 +1,22 @@
+def subsetPrint(list):
+
+    #If list is equal to an empty list return the empty list as a sublist (subset)
+    if list == [] :
+        return [[]]
+
+    """ """
+    return [[list[0]]+y for y in subsetPrint(list[1:])] +subsetPrint(list[1:])
+
+print(subsetPrint([3,2,1]))
+
+#Non recursive LeetCode 78
+
+def subsets(list):
+    output=[[]]
+
+    for i in list:
+        output+= [lst + [i] for lst in output]
+    
+    return output
+
+print(subsets([3,2,1]))