71 lines
2.1 KiB
Zig
71 lines
2.1 KiB
Zig
const std = @import("std");
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// NOTE: I know this is way too overengineered, but I wanted
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// to make it as efficient as possible.
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pub fn main() !void {
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const input = @embedFile("input");
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// Putting part 1's solution as an extra :P
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std.debug.print("Part 1's solution: {}\n", .{sumTopNElves(input, 1)});
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std.debug.print("Part 2's solution: {}\n", .{sumTopNElves(input, 3)});
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}
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// Returns the sum of the <cant> elves with the most calories from <string>
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pub fn sumTopNElves(input: []const u8, comptime cant: usize) usize {
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var iter = ElfIterator.init(input);
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// Initialize the buffer where the 3 numbers will lie
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var maxArr: [cant]usize = .{0} ** cant;
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// Keeps track of which is the smallest index of the array
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var min_i: usize = 0;
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// Iterate through each elf's sum of calories as usize
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while (iter.next()) |elf| {
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// Check if the current elf carries more
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// calories than the previous smallest max
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if (elf > maxArr[min_i]) {
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maxArr[min_i] = elf;
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// maxArr changed, update what is the smallest index
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var advance: usize = 1;
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while (advance < cant) : (advance += 1) {
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// Advance and wrap around
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const i = (min_i + advance) % cant;
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if (maxArr[i] < maxArr[min_i]) min_i = i;
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}
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}
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}
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var res: usize = 0;
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inline for (maxArr) |num| {
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res += num;
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}
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return res;
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}
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// Helper to return the total of calories per elf one at a time
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const ElfIterator = struct {
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iter: std.mem.SplitIterator(u8),
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pub fn init(input: []const u8) ElfIterator {
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return ElfIterator{
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// We assume the input file is properly formatted
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.iter = std.mem.split(u8, input, "\n"),
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};
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}
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pub fn next(self: *ElfIterator) ?usize {
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var res: usize = 0;
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while (self.iter.next()) |calories| {
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// If non numeric assume EOF (End Of elF)
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res += std.fmt.parseInt(usize, calories, 10) catch return res;
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}
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// If we reach EOF (End Of File, do not confuse with End Of elF), return null
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return null;
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}
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};
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