ejri.dev
1const std = @import("std");
2const Allocator = std.mem.Allocator;
3
4pub fn run(_: Allocator, input: []u8) !struct { u64, u64 } {
5 var lines = std.mem.tokenizeScalar(u8, input, '\n');
6
7 var answer1: u64 = 0;
8 var answer2: u64 = 0;
9 while (lines.next()) |line| {
10 answer1 += try calculateJoltage(line, 2);
11 answer2 += try calculateJoltage(line, 12);
12 }
13
14 return .{ answer1, answer2 };
15}
16
17fn calculateJoltage(line: []const u8, num_digits: usize) !u64 {
18 var index: usize = 0;
19 var value: usize = 0;
20 var total: usize = 0;
21 for (0..num_digits) |i| {
22 const start = if (i == 0) 0 else index + 1;
23 const end = line.len - (num_digits - i - 1);
24
25 index = std.mem.indexOfMax(u8, line[start..end]) + start;
26 value = try std.fmt.charToDigit(line[index], 10);
27
28 total += value * std.math.pow(usize, 10, num_digits - i - 1);
29 }
30
31 return total;
32}