Learn From Here

Author: Hamza-Sahapurwala

10thRecursioninPython.py

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+
+# ! Recursion
+
+# * Calling a function while the function itself is running
+
+# * We can use the above property to solve problems
+
+# * To use the above thing, the criteria of writing a recursive functions:
+
+# * Base Case: The condition to stop recursion at this point
+
+# * Recursive Case: Anything which is not the base case but takes some step towards the base case
+
+# * Recursive Fucntions work like STACKS!!!
+
+# * Using Recursive functions to find factorial of a no.
+
+# * Depth: No. of steps to complete a problem
+
+# Advantages:
+
+# 1. Used to simplify complex problems into smaller easier problems
+
+# 2. Solving problems with repeated patterns
+
+# 3. Handling unknown levels of depth
+
+# 4. Mathematical & Algorithmic
+
+def factorial(n):
+
+    if n == 0: # * Base Case
+
+        return 1
+    
+    else: # * Recursive Case
+
+        return n * factorial(n - 1) # * This calls the function again and again until the argument doesn't become 0 to reach the base case and
+    
+    # * from there the functins keep repeating their values to their callers coming to this place at last which gives us the answer
+
+print(factorial(5))
+
+# * Using Recursive Function, find GCD b/w two no.
+
+def gcd(a, b):
+
+    if b == 0:
+
+        return a
+    
+    else:
+
+        return gcd(b, a % b)
+    
+print(gcd(91,65))
+
+# * Using Recursive Function, print out the Fibonnaci Series
+
+def fibonnaci(n):
+
+    if n <= 1: # * Base Case
+
+        return n
+
+    else: # * Recursive Case
+
+        return fibonnaci(n - 1) + fibonnaci(n - 2) # * Because Fibonnaci Series is basically nth postion no. = (n-2)th position no. + (n-1)th position no.
+
+for i in range(0,6):
+
+    print(fibonnaci(i),end = ' ') # * At that index, it returns the fibonnaci no. present there
+
+print()
+
+# * Using Recursive Function, print out the the Movements for the game of Tower of Hanoi
+
+i = 0
+
+def toh(n, src, aux, des):
+
+    global i
+
+    if n == 1:
+
+        i+=1
+
+        print(f'Move Disk 1 from source {src} to destination {des}.')
+
+    else:
+
+        i+=1
+
+        toh(n - 1, src, des, aux)
+
+        print(f'Move Disk {n} from source {src} to destination {aux}.')
+
+        toh(n - 1, aux, src, des)
+
+toh(6,'A','B','C')
+
+print('The no. of moves it takes to solve the Tower of Hanoi',i)
+
+# * Using Recursive function to print a simple pattern
+
+def pattern(n):
+
+    if n == 0: # * Base Case
+
+        return
+    
+    print('*')
+
+    pattern(n-1)
+
+pattern(5)
+
+# * Using Recursive function to add two no.
+
+def add(x,y):
+
+    if y == 0: # * Base Case
+
+        return x
+
+    return add(x,y-1) + 1
+
+# * Using Recursive function to subtract two no.
+
+def sub(x,y):
+
+    if y == 0: # * Base Case
+
+        return x
+
+    return sub(x - 1,y - 1)
+
+# * Using Recursive function to multiply two no.
+
+def mul(x,y):
+
+    if x < y:
+
+        return mul(y,x)
+
+    elif y != 0:
+
+        return x + mul(x, y - 1)
+
+    else: # * Base Case
+
+        return 0
+
+# * Using Recursive function to divide two no.
+
+def div(x,y):
+
+    if x < y: # * Base Case
+
+        return 0
+
+    else:
+
+        return 1 + div(x-y, y)

11thCallbackinPython.py

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+
+# ! Callback Functions
+
+# * Callback using built-in functions
+
+s = ['Hello', 'Welcome', 'to', 'python','world']
+
+print(sorted(s))
+
+print(sorted(s, key=str.upper))
+
+# * Callback using User-Defined functions
+
+def function_name(x):
+
+    return x[0] * x[1]
+
+def c(f,x): 
+
+    print(f) # * Returns something which relates to the function created above
+
+    return f(x) # * Calls the above function
+
+print(c(function_name, [3,23]))
+
+# * Multiple Callback Functions
+
+def fun(fun_list, x, y):
+
+    for i in fun_list: # * i will have go through the list
+
+        print(i)
+
+        i(x, y) # * Functions are called respectively
+
+def a(x, y):
+
+    print(x + y)
+
+def d(x, y):
+
+    print(x // y)
+
+c = [a, d] # * a and d are the function names
+
+fun(c, 10, 5)