CMU 15-112: Fundamentals of Programming and Computer Science
Extra Practice for Week 4 (Due never) Code Tracing (CT) Exercises

1. Trace #1:
   
   import copy def ct1(L): a = L b = copy.copy(L) c = copy.deepcopy(L) b[1][1] = c[0][0] c[1].append(b[1][0]) a[0] = b[1] a[0][0] += b.pop()[0] return a,b,c L = [[1],[2,5]] for val in ct1(L): print(val) print(L)


2. Trace #2:
   
   def ct2(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(ct2(lst)) print(lst)


3. Trace #3:
   
   import copy def ct3(L): a = L b = copy.copy(L) c = copy.deepcopy(L) b[0] = a[1] * a[1][0] a[0][0] += a.pop()[0] b[1] = c[0] return b # Be careful to get the brackets and commas right! L = [[1],[2],[3]] print(ct3(L)) print(L)


4. Trace #4:
   
   import copy def ct4(L): a = L b = copy.copy(L) c = copy.deepcopy(L) a[0] = b[1] b[1][1] = c[0] c[1].append(b[1]) a[0][0] += (b[1].pop())[0] return (a,b,c) # Be careful to get the brackets and commas right! for val in ct4([[1],[2,5]]): print(val) # prints 3 lines


5. Trace #5:
   
   import copy def ct5(a): b = a (a, c, d) = (b + [b[0]], copy.copy(b), copy.deepcopy(b)) d[1] = b[0] c[1] = d[0] b = b[0:1] + b[1:] b[0] = [3,4] a[0] += [5] c[1][0] = 1 + b[0][1] a[0][0] = 6 + d[1][0] for (s,L) in (("a",a), ("b",b), ("c",c), ("d",d)): print(s,L) a = [list(range(2-i)) for i in range(2)] print("start:", a) ct5(a) print("end:", a)