Hi;

To learn D better and challanging myself I am tring code computation's with D.

There is a question which is about reading a line of integer which consist of 200000 elements.

My solution fails because "Time limit exceeded", I thought it is because of my algorithm first. I realize time limit is exceeded even before my algorithm starts while reading line of integers. I understand this by giving a wrong answer to question after readln statement. I did that to get a "wrong answer error" but my code still get a "Time limit exceed" error because "readln" takes very long time.

Can I achieve something faster than code below?

auto peopleMoney = stdin.readln().split().map!(a => to!int(a)).array();
if (peopleMoney.length == 200000)
	 writeln(":(");

Regards
Erdem


Ps: I do not want to bore you with long code, but I am sending link to whole program anyway if anyone need.
 http://codeforces.com/contest/549/submission/11537206

On Thursday, 11 June 2015 at 19:56:00 UTC, kerdemdemir wrote:
> Hi;
>
> To learn D better and challanging myself I am tring code computation's with D.
>
> There is a question which is about reading a line of integer which consist of 200000 elements.
>
> My solution fails because "Time limit exceeded", I thought it is because of my algorithm first. I realize time limit is exceeded even before my algorithm starts while reading line of integers. I understand this by giving a wrong answer to question after readln statement. I did that to get a "wrong answer error" but my code still get a "Time limit exceed" error because "readln" takes very long time.
>
> Can I achieve something faster than code below?
>
> auto peopleMoney = stdin.readln().split().map!(a => to!int(a)).array();
> if (peopleMoney.length == 200000)
> 	 writeln(":(");
>
> Regards
> Erdem
>
>
> Ps: I do not want to bore you with long code, but I am sending link to whole program anyway if anyone need.
>  http://codeforces.com/contest/549/submission/11537206

Your algorithm works for about quadratic time. For N = 200000 your algorithm will work terribly long. The function `readln()` nothing to do with:
http://codeforces.com/contest/549/submission/11476513

A faster way of `scanf`, but it will not help you, because your algorithm is slow.

On Thursday, 11 June 2015 at 19:56:00 UTC, kerdemdemir wrote:
> Can I achieve something faster than code below?
>
> auto peopleMoney = stdin.readln().split().map!(a => to!int(a)).array();
> if (peopleMoney.length == 200000)
> 	 writeln(":(");

`std.array.split` is eager. It may be faster if you use the lazy `std.algorithm.splitter`:

auto peopleMoney = stdin.readln().splitter().map!(to!int).array();

[...]
> Ps: I do not want to bore you with long code, but I am sending link to whole program anyway if anyone need.
>  http://codeforces.com/contest/549/submission/11537206

Seeing that you get the number of elements beforehand, you can preallocate the array, avoiding relocations of the data as elements are appended:

peopleMoney = new int[peopleCount];
copy(stdin.readln().splitter().map!(to!int), peopleMoney);

But these are tweaks. They may improve performance a little, but it won't be drastic.

And anyway, I find it hard to believe that the original version takes more than a second to parse the input. Maybe try returning from the function in addition to printing ":(". Otherwise the program goes on, and the site may not show the output if the program as a whole took too long.

Thanks a lot for your great advices and exaamples. Yes if I don't return; web-site won't show it as "wrong answer".

As a learner I am very happy with the responsiveness of the community.

Regards