55 lines
1.7 KiB
Zig
55 lines
1.7 KiB
Zig
const std = @import("std");
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const example = @embedFile("example");
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const input = @embedFile("input");
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pub fn main() anyerror!void {
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var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
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defer arena.deinit();
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const allocator = arena.allocator();
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try std.testing.expectEqual(try solve(example, allocator), 95437);
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const result = try solve(input, allocator);
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try std.io.getStdOut().writer().print("{}\n", .{result});
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}
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fn solve(puzzle: []const u8, allocator: std.mem.Allocator) !u64 {
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var it = std.mem.tokenize(u8, puzzle, "\n");
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var tot: usize = 0;
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var n: usize = 0; // depth
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var stack = std.ArrayList(u64).init(allocator);
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_ = it.next() orelse unreachable; // drop the cd /
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try stack.append(0);
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while (it.next()) |line| {
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if (line[2] == 'c') { // a cd command
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if (line[5] == '.') { // going up
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const v = stack.pop();
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n -= 1;
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stack.items[n] += v;
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if (v <= 100000) {
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tot += v;
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}
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} else { // going down
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n += 1;
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try stack.append(0);
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}
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} else if (line[2] == 'l') { // a ls command
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continue;
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} else if (line[2] == 'r') { // a dir entry in a ls command
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continue;
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} else { // a file entry in a ls command
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var elts = std.mem.split(u8, line, " ");
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const v = try std.fmt.parseInt(u64, elts.next() orelse unreachable, 10);
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stack.items[n] += v;
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}
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}
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while (n > 1) : (n -= 1) {
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const v = stack.pop();
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n -= 1;
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stack.items[n] += v;
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if (v <= 100000) {
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tot += v;
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}
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}
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return tot;
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}
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