Google Code Jam 2011 Language Usage

[bearophile]

Andrew Wiley:

> The main thing that frustrated me was that getting input in D wasn't
> anywhere near as straightforward as it is in Java. For the first problem,

I have tried to implement a D solution to the first problem, because its input is a bit more complex. I have used C++ code written the winner as starting point. After several failed D versions (this is BAD for D2/Phobos), I've written a Python prototype and then I have translated it to D2:

import std.stdio, std.math, std.conv, std.string, std.array, std.algorithm;

auto next(R)(ref R range) {
   auto result = range.front();
   range.popFront();
   return result;
}

void main() {
    auto fin = File("input.txt");
    auto fout = File("output.txt", "w");
    foreach (i; 0 .. to!int(fin.readln().strip())) {
        int[2] lastP = 1;
        int[2] lastT = 0;
        int t = 0;
        auto parts = splitter(fin.readln().strip(), " ");
        foreach (_; 0 .. to!int(next(parts))) {
            string s = next(parts);
            int q = to!int(next(parts));
            int id = cast(int)(s == "B");
            t = max(t, abs(q - lastP[id]) + lastT[id]) + 1;
            lastP[id] = q;
            lastT[id] = t;
        }
        fout.writefln("Case #%d: %d", i, t);
    }
}


Three problems I've found in translating the prototype:

- A next() function/method is missing, but I needed it, so I have had to define it, to keep code from becoming hairy and quite less readable.


to!int expects a stripped string. In my code I am never sure to have a stripped string coming from input, so I have to always add a strip(), this is dumb:
foreach (i; 0 .. to!int(fin.readln().strip())) {
==>
foreach (i; 0 .. to!int(fin.readln())) {


std.algorithm.splitter() doesn't default to splitting on whitespace as std.string.split() does. This is bad because in this program I need to add a strip() and in general it's bad because if there are two spaces, or a newline, it causes a mess, so I'd like a new overload of splitter() that acts as split():
auto parts = splitter(fin.readln().strip(), " ");
==>
auto parts = splitter(fin.readln());

Bye,
bearophile