Where am I going wrong in this python code for CLRS exercise 2.1-4

Question

So the problem is: "Consider a problem of adding two n-bit binary integers, stored in two n-element arrays A and B. The sum of the two integers should be stored in binary form in an (n+1)-element array C. State the problem formally and write pseudocode for adding the two integers."

and my python code for this problem is:

A = [1,0,1,1,0,1,0]
B = [1,1,1,0,1,0,0]
n = len(A)
C = [0,0,0,0,0,0,0,0]

for i in range(0, n):
    C[i] = A[i] + B[i] + C[i]
    if C[i] == 2:
        C[i] = 0
        C[i+1] == 1
    elif C[i] == 3:
        C[i] = 1
        C[i+1] = 1


print C

Also I have taken the least significant digits on the left which I can reverse after I've done the calculation.

I cant figure out what the mistake is please help!

Just a note: If you plan on having A & B taken in via input, an easier way to define `C` would be `C=[0]*(n+1)`, which auto generates the array you want. — Emad Y, Jul 08 '15 at 18:55

score 5 · Accepted Answer · answered Jul 08 '15 at 18:51

5

C[i+1] == 1 does a comparison, not an assignment.

answered Jul 08 '15 at 18:51

jtbandes

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ksha · Answer 2 · 2016-09-10T13:34:13.800

0

In case, you like a slight modification for the sake of brevity (pseudocode):

for i = C.length to i = 2
  C[i] = C[i] + A[i-1] + B[i-1]
  if C[i] > 1
    C[i-1] = C[i-1] + 1
    C[i] = C[i] - 2

edited Sep 10 '16 at 13:34

answered May 28 '16 at 19:20

ksha

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Where am I going wrong in this python code for CLRS exercise 2.1-4

2 Answers2