66 lines
2.0 KiB
Zig
66 lines
2.0 KiB
Zig
const std = @import("std");
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const Io = std.Io;
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const shared = @import("shared.zig");
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const print = shared.print;
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var buf: [4096]u8 = undefined;
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fn repeatCountFromStart(needle: []const u8, haystack: []const u8) usize {
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var off: usize = 0;
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var count: usize = 0;
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while (off + needle.len <= haystack.len and std.mem.eql(u8, needle, haystack[off .. off + needle.len])) {
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count += 1;
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off += needle.len;
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}
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return count;
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}
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pub fn main(init: std.process.Init) !void {
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try shared.sharedInit(init);
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const allocator: std.mem.Allocator = init.arena.allocator();
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const bytes = shared.loadBytesArg(allocator);
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var tok = std.mem.tokenizeScalar(u8, bytes, ',');
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var part1: i64 = 0;
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var part2: i64 = 0;
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while (tok.next()) |next| {
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var splitIter = std.mem.splitAny(u8, next, "-");
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var v: [2]i64 = .{ 0, 0 };
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var i: usize = 0;
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while (splitIter.next()) |s| {
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v[i] = try std.fmt.parseInt(i64, s, 10);
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i += 1;
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if (i > 2) unreachable;
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}
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for (@intCast(v[0])..@intCast(v[1] + 1)) |j| {
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const s = try std.fmt.bufPrint(&buf, "{d}", .{j});
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const left = s[0..(s.len >> 1)];
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if (s.len % 2 == 0 and shared.countInstancesOf(s, left) == 2) {
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part1 += @intCast(j);
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}
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{
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var h: usize = s.len + 1;
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while (h - 1 > 0) : (h -= 1) {
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const count = repeatCountFromStart(s[0 .. h - 1], s);
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// print("{s} {d} count{d} s.len{d}", .{ s[0 .. h - 1], j, count, s.len });
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if (count * (h - 1) == s.len and count != 1) {
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// print("{s} yay! {d} count{d}", .{ s[0 .. h - 1], j, count });
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part2 += @intCast(j);
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break;
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} else {
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//print("{s}", .{s[0..h]});
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}
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}
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}
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}
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}
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print("part1 {d} part2 {d}", .{ part1, part2 });
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}
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