HW 2.6 works for all cases but marked incorrect..

0 
def find_first(search,target):
    first=search.find(target)
        if first==-1:
            print -1
            return -1
        else:
            return search.find(target)

def find_last(search,target):
    if find_first(search,target)!=-1:
        next=find_first(search,target)
        while 1:
            a,next=search.find(target,next),search.find(target,next+1)
            #print next
            if next==-1:
                print a
                return a

asked 07 Mar '12, 20:53

Ashenafi%20Tadesse%20Mulat's gravatar image

Ashenafi Tad...
37●6
accept rate: 100%

edited 07 Mar '12, 21:19

Thom%20Blake's gravatar image

Thom Blake
4.4k●10●46●81
4 Answers:
0

The problem is, that you have two print calls (one in find_first, the other in find_last) which outputs two values on one call to find_last, which is not correct, you should always print just one value on every call.

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answered 07 Mar '12, 20:59

implicit_knowledge's gravatar image

implicit_kno...
3.7k●8●28●58
1

One code path in your find_last function fails to return value. That is find_last never execute return statement when find_first returns -1.

Correct version:

def find_last(search,target):
  if find_first(search,target)!=-1:
    next=find_first(search,target)
    while 1:
        a,next=search.find(target,next),search.find(target,next+1)
        #print next
        if next==-1:
            print a
            return a
  else:
    return -1
link

answered 07 Mar '12, 21:05

red75prim's gravatar image

red75prim
47●5
0

Your code print None instead of -1 when there is no match, try to check this:

print find_last('aaaa', 'b')

link

answered 07 Mar '12, 21:00

Lele's gravatar image

Lele
2.7k●3●15●34

i tried it .. it prints -1 .. please check it ..

(07 Mar '12, 21:10) Ashenafi Tad... Ashenafi%20Tadesse%20Mulat's gravatar image
0

thank you guys for your fast response..I will try to re-write it based on your suggestion

link

answered 07 Mar '12, 21:16

Ashenafi%20Tadesse%20Mulat's gravatar image

Ashenafi Tad...
37●6
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Asked: 07 Mar '12, 20:53

Seen: 95 times

Last updated: 07 Mar '12, 21:19

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