Extra Practice for Week 4 (Due never) Code Tracing (CT) Exercises

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These problems will help you prepare for hw4 and quiz4. They are optional and you are encouraged to collaborate when working on them.

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Code Tracing (CT)
What will each of these print?

1. def ct(a, b):
       a += [3]
       a = a + [4]
       for c in a:
           for i in range(len(b)):
               if (b[i] not in a):
                   print("A", end="")
                   b[i] += c
               elif (c % 2 == 1):
                   print("B", end="")
                   b += [c]
               elif (b[-1] != c):
                   print("C", end="")
                   b = b + [c]
       return (a,b)
   a = [4]
   b = [2,3]
   print(ct(a,b))
   print(a,b)

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2. def ct(L):
       result = [ ]
       M = [L[i]*10**i for i in range(len(L))]
       for val in M:
           result.extend([val, L.pop()])
       return result
   L = [2,5,3]
   M = ct(L)
   print(L, M)

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3. def ct(L):
       result = [ ]
       M = L[:] # same as M = copy.copy(L)
       if (M == L): result.append(1)
       if (M is L): result.append(2)
       if (M[0] == L[0]): result.append(3)
       if (M[0] is L[0]): result.append(4)
       return result
   print(ct([5,7,6]))

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4. def ct(L):
       M = L
       L += [4]
       M = M + [5]
       print(L, M)
   ct(list(range(1)))

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5. import copy
   
   a = [1,2,3,4]
   (b,c) = (a, copy.copy(a))
   print((a == b), (a == c))
   print((a is b), (a is c))
   print((a[0] is b[0]), (a[0] is c[0]))
   a = [1,2]
   (b,c) = (a, copy.copy(a))
   b[0] += 10
   c[1] += 100
   for L in [a,b,c]: print(L) 
   
   a = [1,2]
   (b,c) = (a, copy.copy(a))
   a[0] += 1
   b[0] += 2
   c[1] += 3
   a[0] = c[0]
   b[0] = a[1]
   
   for L in [a,b,c]: print(L)
   print()
   
   a = list(range(2,10,7))
   (b, c) = (a, a[:2]) 
   b[0] += 3
   a += [3]
   a = a + [4]
   print(c + [b[0]])
   print(c.append(b[1]))
   print(a, b, c)

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6. import copy
   
   def f(a, b):
       a = copy.copy(a) 
       a[0] = b[1]
       b[0] = a[1] 
       return a + b
   a1 = a2 = list(range(5,7))
   b1 = b2 = list(range(2))
   a1 = f(a1, b1)
   print(a1, a2, b1, b2)

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7. def onesDigit(n):
       return n%10
   
   def ct(L):
       for i in range(len(L)):
           L[i] += sum(L) + max(L)
       return sorted(L, key=onesDigit)
   a = [2,1,0]
   print(ct(a))
   print(a)

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8. def ct(a):
       a[1] = "foo"
       a[0], a[2] = a[2], a[0]
       print(a)
       b = a
       b.extend([42, "wow" ])
       b.pop()
       print(b)
       c = [] + b
       c[1:-1] = ["Hello" , "World" ]
       return c
   lst = [15, "1" , "twelve" ]
   print(ct(lst))
   print(lst)

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