CMU 15-112: Fundamentals of Programming and Computer Science
Extra Practice for Week 2 (Due never) Code Tracing (CT) and Reasoning Over Code (ROC) Exercises

1. def ct1(n,m): for i in range(n, 7): for j in range(m, -2, -1): i = abs(i) j = abs(j) if i % 2 == 0: print("even", i) elif i > 0: print("foo", i) if j % 2 == 1: print("odd", j) if j > 0: print("bar", j) print("almost done!") print("done!") ct1(5,-1)


2. def ct2(m, n): total = 0 for x in range(m, n+1, 3): print('x =', x) total += x for y in range(m, m+2): print('y = ', y) total += y return total print(ct2(1,9))


3. def ct3(z): total = 0 for y in range(z,1,-1): if (y % 2 == 0): print('skip y =', y) continue total += y if (total > 20): print('break at y =', y) break return total print(ct3(10))


4. def ct4(n, m): for i in range(1, 2*n, n): for j in range(-m, -1, m//3): if(i % 4 == j): print("mod", i, j) if(i == j): print("equal", i, j) elif(j > i): print("greater", i, j) else: break ct4(2, -5)


5. def ct5(x): y = 3 while True: print(y, end=' ') for z in range(1, x*y, 2): if (z % 3 == 1): print(z, end=' '); continue y += x if (y % 5 > 0): print(y, end=' ') break print(y, end=' ') if (y > 10): return x y += 1 print(ct5(7))

1. def rc1(n): if ((not isinstance(n, int)) or (n > 100)): return False total = 0 while (n > 0): total = 10*total + n%10 n //= 10 return (total == 42)


2. def f(n): if (n == 0): return 1 n = abs(n) count = 0 while (n > 0): count += 1 n //= 10 return count def rc2(m): if (not(isinstance(m, int)) or (m < 0)): return False start = 0 while True: count = 0 for n in range(start, start+3): count += f(n) if (count > 9): break start += 1 return (m == start)


3. def rc3(m): if ((not isinstance(m, int)) or (m < 0)): return False x = 1 while (x < m//2): x += 10 return (x + m == 60)


4. def rc4(n): if (n == 0): return False count = 0 for x in range(0, 100, n): count += 1 return ((count == 5) and (x//10 == x%10 + 4))