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aoc-2020/source/day9.d

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D

import std.array;
import std.algorithm;
import std.range;
import std.stdio;
import std.traits;
import std.variant;
import dayutil;
Variant run(int part, File input, bool bigboy, string[] args) {
import std.conv;
auto numbers = input.byLineCopy.array.map!(to!uint);
return Variant(parts!uint(part,
() => part1(numbers)));
}
T part1(Range, T = ElementType!Range)(Range range, int preambleSize = 25)
if (isForwardRange!Range && isNumeric!T) {
foreach(window; range.slide!(No.withPartial)(preambleSize + 1)) {
if(!window[0..preambleSize].any!(e => window.canFind!(x => e + x == window[preambleSize]))) {
return window[preambleSize];
}
}
return -1;
}
unittest {
int[] numbers = [35, 20, 15, 25, 47, 40, 62, 55, 65, 95, 102, 117, 150, 182, 127, 219, 299,
277, 309, 576];
assert(part1(numbers, 5) == 127);
}