### Author Topic: ( Challenge ) How many 'carrys'?  (Read 6496 times)

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#### Mark

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• Posts: 28762
##### ( Challenge ) How many 'carrys'?
« on: March 18, 2009, 11:00:55 AM »
It has been a long time since we have had a challenge around here. I hope this one keeps you occupied for a little while.

When you do addition you 'carry' the 1 if the total is greater than 9. For example if we add 109 and 209 we would have one 'carry';

Quote
1  <- one 'carry'
109
209
---
318

Challenge:
given two integers return how many 'carrys' we have.

The attached file has a two integers per line, you can use it or user input.

Not my idea, it was borrowed.

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#### JohnK

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• Posts: 10623
##### Re: ( Challenge ) How many 'carrys'?
« Reply #1 on: March 18, 2009, 11:35:00 AM »
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#### VovKa

• Water Moccasin
• Posts: 1628
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##### Re: ( Challenge ) How many 'carrys'?
« Reply #2 on: March 18, 2009, 12:41:29 PM »
Code: [Select]
(defun test (n1 n2)
(if (or (zerop n1) (zerop n2))
0
(if (< 9 (+ (rem n1 10) (rem n2 10)))
(1+ (if (= 9 (rem (/ n1 10) 10))
(test (/ n1 10)
(if (= 9 (rem (/ n2 10) 10))
(/ n2 10)
(1+ (/ n2 10))
)
)
(test (1+ (/ n1 10)) (/ n2 10))
)
)
(test (/ n1 10) (/ n2 10))
)
)
)
« Last Edit: March 18, 2009, 01:18:57 PM by VovKa »

#### gile

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• Posts: 2507
• Marseille, France
##### Re: ( Challenge ) How many 'carrys'?
« Reply #3 on: March 18, 2009, 12:53:59 PM »
Very nice Vovka !
Speaking English as a French Frog

#### SomeCallMeDave

• Guest
##### Re: ( Challenge ) How many 'carrys'?
« Reply #4 on: March 18, 2009, 01:14:01 PM »
Does it have to be a LISP solution?

I have been playing with Ruby and cobbled this one together

Code: [Select]
def count_the_carry(string1, string2)
#assumes strings are same length and numeric
array1 = string1.split(//).collect{|x| x.to_i}
array2 = string2.split(//).collect{|x| x.to_i}
sum_array = Array.new
array1.size.times {|i| sum_array[i]=array1[i]+array2[i]}
carry_count = 0
sum_array.each {|x| carry_count += 1 if x >=10}
carry_count
end

input_file = File.new("c:/jobs/random_ints.txt", "r" )
output_file = File.new("c:/jobs/counts.txt", "w")
while (line = input_file.gets)
nums = line.split
count = count_the_carry(nums[0], nums[1])
output_file.write(count.to_s + "\n")
end
input_file.close
output_file.close

#### VovKa

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• Posts: 1628
• Ukraine
##### Re: ( Challenge ) How many 'carrys'?
« Reply #5 on: March 18, 2009, 01:21:24 PM »
thanx gile
i'm sorry but there was a mistake in the routine
i hope now it's ok

#### Mark

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• Posts: 28762
##### Re: ( Challenge ) How many 'carrys'?
« Reply #6 on: March 18, 2009, 01:43:55 PM »
Does it have to be a LISP solution?

Nope!
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#### SomeCallMeDave

• Guest
##### Re: ( Challenge ) How many 'carrys'?
« Reply #7 on: March 18, 2009, 02:01:10 PM »
Thanks, Mark.

Not only did I not read the original post correctly, I posted a solution that doesn't work.

There is a particular case where my algorithm fails.  I won't spoil everyone else's fun by post it now.

Back to the drawing board for me.  At least Ruby is fun to play with.

#### Tuoni

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• Posts: 3032
• I do stuff, and things!
##### Re: ( Challenge ) How many 'carrys'?
« Reply #8 on: March 18, 2009, 02:17:21 PM »
For example if we add 109 and 209 we would have one 'carry';

...

To me that's two carries... you carry once into the 10's column then once into the 100's column?  Am I alone in this?

#### ElpanovEvgeniy

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• Posts: 1569
• Moscow (Russia)
##### Re: ( Challenge ) How many 'carrys'?
« Reply #9 on: March 18, 2009, 02:25:29 PM »
Code: [Select]
(defun test1 (a b)
(if (zerop a)
0
(+ (/ (+ (rem a 10) (rem b 10)) 10) (test1 (/ a 10) (/ b 10)))
) ;_  if
)

#### ronjonp

• Needs a day job
• Posts: 7527
##### Re: ( Challenge ) How many 'carrys'?
« Reply #10 on: March 18, 2009, 02:30:47 PM »
Code: [Select]
(defun test1 (a b)
(if (zerop a)
0
(+ (/ (+ (rem a 10) (rem b 10)) 10) (test1 (/ a 10) (/ b 10)))
) ;_  if
)

That's slick :kewl:

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#### VovKa

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• Posts: 1628
• Ukraine
##### Re: ( Challenge ) How many 'carrys'?
« Reply #11 on: March 18, 2009, 02:32:05 PM »
ElpanovEvgeniy,
(test1 89 11) -> 1
should be 2

#### ElpanovEvgeniy

• Water Moccasin
• Posts: 1569
• Moscow (Russia)
##### Re: ( Challenge ) How many 'carrys'?
« Reply #12 on: March 18, 2009, 02:37:52 PM »
To me that's two carries... you carry once into the 10's column then once into the 100's column?  Am I alone in this?

Code: [Select]
(defun test-lst (l)
;;;(test-lst '(250 250 259 259))
(if (cdr l)
((lambda (a)
(+ a (test-lst (cons a (vl-remove 0 (mapcar '(lambda (a) (/ a 10)) l)))))
)
(/ (apply '+ (mapcar '(lambda (a) (rem a 10)) l)) 10)
)
0
) ;_  if
)

#### ElpanovEvgeniy

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• Posts: 1569
• Moscow (Russia)
##### Re: ( Challenge ) How many 'carrys'?
« Reply #13 on: March 18, 2009, 02:41:46 PM »
ElpanovEvgeniy,
(test1 89 11) -> 1
should be 2

Correction:
Code: [Select]
(defun test1 (a b)
(if (zerop a)
0
((lambda (c) (+ c (test1 (/ (+ c a) 10) (/ b 10))))
(/ (+ (rem a 10) (rem b 10)) 10)
)
) ;_  if
)

#### VovKa

• Water Moccasin
• Posts: 1628
• Ukraine
##### Re: ( Challenge ) How many 'carrys'?
« Reply #14 on: March 18, 2009, 02:45:54 PM »
ElpanovEvgeniy,
(test1 99 11) -> 1
should be 2