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const std = @import("std");
const print = std.debug.print;
pub fn solve(part: []u8, reader: *std.Io.Reader, _: std.mem.Allocator) !void {
if (std.mem.eql(u8, part, "1")) {
try part1(reader);
} else {
try part2(reader);
}
}
fn digits(number: usize) usize {
var value = number;
var n: usize = 0;
while (value != 0) : (value /= 10) {
n += 1;
}
return n;
}
fn part1(reader: *std.Io.Reader) !void {
var output: usize = 0;
while (reader.takeDelimiter(',')) |line| {
const trimmed = std.mem.trimRight(u8, line.?, &[_]u8{'\n'});
if (trimmed.len == 0) break;
var split = std.mem.splitScalar(u8, trimmed, '-');
var start = try std.fmt.parseInt(usize, split.next().?, 10);
const end = try std.fmt.parseInt(usize, split.next().?, 10);
while (start <= end): (start += 1) {
const n = digits(start);
if (n % 2 == 0 and start % std.math.pow(usize, 10,n/2) == start / std.math.pow(usize, 10,n/2)) {
output += start;
start += std.math.pow(usize, 2,n/2);
}
}
} else |_| {
}
print("{d}\n", .{output});
}
fn part2(reader: *std.Io.Reader) !void {
var output: usize = 0;
while (reader.takeDelimiter(',')) |line| {
const trimmed = std.mem.trimRight(u8, line.?, &[_]u8{'\n'});
if (trimmed.len == 0) break;
var split = std.mem.splitScalar(u8, trimmed, '-');
var start = try std.fmt.parseInt(usize, split.next().?, 10);
const end = try std.fmt.parseInt(usize, split.next().?, 10);
while (start <= end): (start += 1) {
const n = digits(start);
for (1..n) |i| {
if (n % i == 0) {
const p: usize = std.math.pow(usize, 10,i);
if (start % p != 0) {
const div = start / (start % p);
var c: usize = 0;
for (0..n/i - 1) |_| {
c *= p;
c += p;
}
c += 1;
if (div == c){
output += start;
start += std.math.pow(usize, 2, n/2);
break;
}
}
}
}
}
} else |_| {
}
print("{d}\n", .{output});
}
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