42 lines
1.2 KiB
Zig
42 lines
1.2 KiB
Zig
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const std = @import("std");
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pub fn main() void {
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const input = @embedFile("input");
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std.debug.print("Part 1: {}\n", .{findDisctinctSubstrIdx(input, 4)});
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std.debug.print("Part 2: {}\n", .{findDisctinctSubstrIdx(input, 14)});
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}
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fn findDisctinctSubstrIdx(input: []const u8, n: usize) usize {
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// Loop through all the groups of 4
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var i: usize = n;
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group: while (i < input.len) : (i += 1) {
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const slice = input[(i - n)..i];
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// See if each one of them is unique in smaller groups.
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// Ex.: is 1 in 234? -> is 2 in 34? -> is 3 in 4?
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var j: usize = 0;
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while (j < slice.len - 1) : (j += 1) {
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const needle = slice[j];
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const haystack = slice[(j + 1)..];
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for (haystack) |blade| {
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// We found a match, throw batch to garbage
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if (needle == blade) {
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// We know this character appears somewhere else in
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// the haystack. As long as this letter is here, this
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// n-letter work will be invalid. Skip ahead.
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i += j;
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continue :group;
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}
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}
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}
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// We found it, get out
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break;
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}
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return i;
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}
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