CODEWITHSUNDEEP
pythonpython-2.7
Liondancer
Liondancer

Reputation: 16479

cracking code interview 1.4

I practicing interview questions from cracking the code interview.

The question is for each space (' ') replace it with '%20'. The end of the string has 2 extra spaces for each space in the string.

For example input: str = "b_g_f_ _ _ _" (underscores represent space. Easier to represent)

output: str2 = "b%20g%20f"

Currently my output is not working properly

input: "b c  "

output: "b%20c%20%20"

correct output: "b%20c"

code:

def editstr(str):
    str2 = ""
    length = len(str)
    count = 0
    while 3*count < length:
        for char in str:
            if ord(char) < 257 and ord(char) >= 0 and ord(char) != 32:
                str2 = str2 + char
                count += 1
            else:
                if ord(char) == 32:
                    str2 = str2 + ("%20")
                    count += 3
    print str2

Upvotes: 0

Views: 1011

Answers (5)

Ratan Kumar
Ratan Kumar

Reputation: 1650

more pythonic :

import urllib
urllib.quote(url.strip())

Following up the discussion above :

urllib.quote(url[:-2]+(url[-2:].strip()))

Upvotes: 0

Emil Davtyan
Emil Davtyan

Reputation: 14089

Is this cheating?

> import urllib
> urllib.quote("b g f     ")
'b%20g%20f%20%20%20%20%20'

Thanks to @SteveJessop I finally understood the question I wasn't sure what was the right output in the example, here is my take on it using generators, maybe it is more efficient :

input = "b g f    "
def generate_str(input):
    new, orig = [len(input)] * 2   
    for i, char in enumerate(input):
        if i == new: 
            break 
        if char == " ":
            new -= 2
            yield "%20"
        else:
            yield char

print ''.join(generate_str(input))

Upvotes: 3

Chris Seymour
Chris Seymour

Reputation: 85875

Maybe I am missing something but what is wrong with just doing:

>>> s = "b f g      "
>>> s.strip().replace(' ','%20')
'b%20f%20g'

Rewriting behaviour that is built right into the language doesn't make you smarter, quite the opposite. Look at it this way:

  • Any Python developer knows exactly what this code does straight away.
  • These function are well documented and tested.
  • I wrote this in ~1% the time it took you to write and test your function.

Upvotes: 4

nneonneo
nneonneo

Reputation: 179602

Python strings are immutable. The extra spaces in the input string are therefore no help if you want to implement such string replacement in Python. If you want to solve a problem in Python, do it in a Pythonic way:

def editstr(s):
    n = s.count(' ')
    if n == 0: return s
    return s[:-2*n/3].replace(' ', '%20')

This removes the "extra" spaces added at the end, and uses .replace to do the actual string replacement.

Upvotes: 3

Fionie
Fionie

Reputation: 11

At the end of the input string, those spaces will not count as part of the conversion. According to ASCII, a space char ‘ ’ is number 32, but a void char, is number 0. This would help you to understand what this problem means by saying enough space at the end of the char array. Besides that, this interview question specified that you should be doing the conversion in place. So try not to create a second string for that.

Upvotes: 0

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