Independence Day weekend puzzler

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the cyclist
the cyclist 2011-7-3
Inspired by an assignment in my son's Java programming class:
Write a one-liner that takes as input an array of numbers (e.g. x = [1 2 3]) and which outputs an array of integers that is "incremented" properly, (in this case, y = [1 2 4]).
Examples of proper input/output:
x = [1 9 1 9] ----> y = [1 9 2 0]
and
x = [9 9 9] ----> y = [1 0 0 0]
No semicolons allowed in your one line!
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Paulo Silva
Paulo Silva 2011-7-4
+1 vote for the interesting puzzler, it's the first vote!
Please vote on it if you found it interesting and you want more of them.

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采纳的回答

Fangjun Jiang
Fangjun Jiang 2011-7-3
I like this Golf challenge. Inspired by Paulo's entry.
num2str(str2num(sprintf('%d',x))+1)-'0'
is shorter.

更多回答（8 个）

Jan
Jan 2011-7-3
My submission is neither a one-liner nor free of semicolons. But the total number of lines and semicolons is less than in STR2NUM and NUM2STR, which have 86 and 217 lines and call INT2STR in addtion.
n = length(x);
q = find(x ~= 9, 1, 'last');
if isempty(q) % [9, 9, 9, ...]
x = 1;
x(n + 1) = 0; % or x = [1, zeros(1, n)]
else % Any non-9 is found
x = [x(1:q - 1), x(q) + 1, zeros(1, n - q)];
end
bym
bym 2011-7-3
kind of a hybrid:
sprintf('%d',sum(x.*10.^(numel(x)-1:-1:0))+1)-'0'
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Jan
Jan 2011-7-4
@David: Which one is your earlier answer?
David Young
David Young 2011-7-4
@Jan: The one that starts with a call to diff

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Andrei Bobrov
Andrei Bobrov 2011-7-3
str2num(num2str(10.^(length(x)-1:-1:0)*x'+1)')'
ADD
z = 10.^(numel(x)-1:-1:0)*x'+1
y = round(rem(fix(z.*10.^-(fix(log10(z)):-1:0))*.1,1)*10)
David Young
David Young 2011-7-3
One-liner, avoiding string operations:
diff([0 (floor((sum(x.*10.^(length(x)-1:-1:0))+1) ./ 10.^(floor(log10(sum(x.*10.^(length(x)-1:-1:0))+1)):-1:0))) .* 10.^(floor(log10(sum(x.*10.^(length(x)-1:-1:0))+1)):-1:0)]) ./ 10.^(floor(log10(sum(x.*10.^(length(x)-1:-1:0))+1)):-1:0)
EDIT: This is only one line of code, even though formatting on the Answers web page makes it look like 4 lines.
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Jan
Jan 2011-7-4
+1: A one-liner without calls to other M-files and therefore even no hidden semicolons.

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Paulo Silva
Paulo Silva 2011-7-3
x=[1 2 3]; %example input
xr=num2str(str2num(strrep(num2str(x),' ',''))+1)-'0'
%xr =[1 2 3 4]
the cyclist
the cyclist 2011-7-3
Here's one just a bit shorter than andrei bobrov's [using numel() to trim one character from length()]:
str2num(num2str(10.^(numel(x)-1:-1:0)*x'+1)')'
Anything shorter?!
David Young
David Young 2011-7-4
Also one line of code (formatting for the web page will display it over more than one line of text):
double(regexprep(char(x), {['([' char(0:8) ']?)(' char(9) '*)$'] ['^(' char(0) '+)$']}, {'${char($1+1)}${regexprep($2,char(9),char(0))}' [char(1) '$1']}))
  1 个评论
David Young
David Young 2011-7-4
This one works for long vectors with thousdands of elements (my arithmetic-based solution doesn't).

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David Young
David Young 2011-7-4
I'm sorry about this one - it's somewhat over the top, and I promise I won't do any more. However, since I think it's a different approach to the others (arithmetic operations but no powers of 10!), here it is:
[ones(1, sum(x)==9*length(x)) x(1:length(x)-sum(cumsum(fliplr(x)) == 9*(1:length(x)))-1) repmat(x(max(1, length(x)-sum(cumsum(fliplr(x)) == 9*(1:length(x)))))+1, 1, sum(x)~=9*length(x)) zeros(1, sum(cumsum(fliplr(x)) == 9*(1:length(x))))]

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