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const std = @import("std");
const mecha = @import("mecha");
const print = std.debug.print;
pub fn solve(part: []u8, buffer: []u8, allocator: std.mem.Allocator) !void {
if (std.mem.eql(u8, part, "1")) {
try part1(buffer, allocator);
} else {
try part2(buffer, allocator);
}
}
fn evaluate(test_value: usize, numbers: []const usize, index: usize) bool {
if (index == 0) {
return test_value == numbers[0];
}
const number = numbers[index];
const division: usize = test_value / number;
if (division * number == test_value) {
const b = evaluate(division, numbers, index - 1);
if (!b and test_value >= number and (test_value - number) % number == 0) return evaluate(test_value - number, numbers, index - 1);
return b;
} else if (test_value >= number) {
return evaluate(test_value - number, numbers, index - 1);
}
return false;
}
fn part1(buffer: []const u8, allocator: std.mem.Allocator) !void {
const parser = mecha.combine(.{ mecha.int(usize, .{}), mecha.string(": ").discard(), mecha.many(mecha.int(usize, .{}), .{ .separator = mecha.string(" ").discard() }) });
var lines = std.mem.splitScalar(u8, buffer, '\n');
var total: usize = 0;
while (lines.next()) |line| {
if (line.len == 0) break;
const parsed = try parser.parse(allocator, line);
const test_value = parsed.value[0];
const numbers: []const usize = parsed.value[1];
if (evaluate(test_value, numbers, numbers.len - 1)) {
total += parsed.value[0];
}
allocator.free(numbers);
}
print("{d}\n", .{total});
}
//----------------------------------------------PART 2--------------------------------------------------------
fn magnitude(int2: usize) usize {
var count: usize = 0;
var temp = int2;
while (temp > 0) {
temp /= 10;
count += 1;
}
return std.math.pow(usize, 10, count);
}
fn evaluate2(test_value: usize, numbers: []usize, index: usize) bool {
if (index == 0) {
return test_value == numbers[0];
}
const number = numbers[index];
const division: usize = test_value / number;
if (division * number == test_value) {
const b = evaluate2(division, numbers, index - 1);
if (b) {
return true;
} else if (test_value >= number and (test_value - number) % number == 0 and evaluate2(test_value - number, numbers, index - 1)) return true;
} else if (test_value >= number and evaluate2(test_value - number, numbers, index - 1)) {
return true;
}
const base = magnitude(number);
if (test_value % base == number) {
return evaluate2(test_value / base, numbers, index - 1);
}
return false;
}
fn part2(buffer: []const u8, allocator: std.mem.Allocator) !void {
const parser = mecha.combine(.{ mecha.int(usize, .{}), mecha.string(": ").discard(), mecha.many(mecha.int(usize, .{}), .{ .separator = mecha.string(" ").discard() }) });
var lines = std.mem.splitScalar(u8, buffer, '\n');
var total: usize = 0;
while (lines.next()) |line| {
if (line.len == 0) break;
const parsed = try parser.parse(allocator, line);
const test_value = parsed.value[0];
const numbers: []usize = parsed.value[1];
if (evaluate2(test_value, numbers, numbers.len - 1)) {
total += parsed.value[0];
}
allocator.free(numbers);
}
print("{d}\n", .{total});
}
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