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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 part1(reader: *std.Io.Reader) !void {
var pos: i32 = 50;
var zero: usize = 0;
while (reader.takeDelimiterInclusive('\n')) |line| {
if (line.len == 0){
break;
}
const numSlice = std.mem.trimRight(u8, line[1..], &[_]u8{'\n'});
const rotations = try std.fmt.parseInt(i32, numSlice, 10);
if (line[0] == 'R') {
pos += rotations;
} else if (line[0] == 'L'){
pos -= rotations;
}
pos = @mod(pos, 100);
if (pos == 0) {
zero += 1;
}
} else |_| {
}
print("{d}\n", .{zero});
}
fn part2(reader: *std.Io.Reader) !void {
var pos: i32 = 50;
var zero: i32 = 0;
while (reader.takeDelimiterInclusive('\n')) |line| {
if (line.len == 0){
break;
}
const numSlice = std.mem.trimRight(u8, line[1..], &[_]u8{'\n'});
var rotations = try std.fmt.parseInt(i32, numSlice, 10);
zero += @divFloor(rotations, 100);
rotations = @rem(rotations, 100);
if (line[0] == 'L'){
rotations *= -1;
}
const with_rotations: i32 = pos + rotations;
const new: i32 = @mod(with_rotations, 100);
if ((new != with_rotations and pos != 0) or new == 0){
zero += 1;
}
pos = new;
} else |_| {}
print("{d}\n", .{zero});
}
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