feat: day 4

src/days/day4.zig

@@ -0,0 +1,74 @@
+const std = @import("std");
+const aoc = @import("../aoc.zig");
+
+pub const info = aoc.DayInfo{
+    .num = 4,
+    .name = "Camp Cleanup",
+};
+
+pub fn part1(alloc: std.mem.Allocator, infile: *std.fs.File) !void {
+    const input = try parse(alloc, infile);
+    defer input.deinit();
+
+    var sum: u32 = 0;
+    for (input.items) |r| {
+        if (rangesFullyContainEachother(r))
+            sum += 1;
+    }
+
+    try std.io.getStdOut().writer().print("{}\n", .{sum});
+}
+
+fn rangesFullyContainEachother(r: [2][2]u32) bool {
+    return (r[0][0] <= r[1][0] and r[0][1] >= r[1][1]) or
+        (r[1][0] <= r[0][0] and r[1][1] >= r[0][1]);
+}
+
+pub fn part2(alloc: std.mem.Allocator, infile: *std.fs.File) !void {
+    const input = try parse(alloc, infile);
+    defer input.deinit();
+
+    var sum: u32 = 0;
+    for (input.items) |r| {
+        if (rangesOverlap(r))
+            sum += 1;
+    }
+
+    try std.io.getStdOut().writer().print("{}\n", .{sum});
+}
+
+fn rangesOverlap(r: [2][2]u32) bool {
+    return r[0][0] <= r[1][1] and r[0][1] >= r[1][0];
+}
+
+fn parse(alloc: std.mem.Allocator, infile: *std.fs.File) !std.ArrayList([2][2]u32) {
+    var entries = std.ArrayList([2][2]u32).init(alloc);
+    errdefer entries.deinit();
+
+    var line_buf: [512]u8 = undefined;
+    while (try infile.reader().readUntilDelimiterOrEof(&line_buf, '\n')) |line| {
+        const trimmed = std.mem.trim(u8, line, &std.ascii.whitespace);
+
+        var entry = std.mem.zeroes([2][2]u32);
+
+        var splits1 = std.mem.tokenize(u8, trimmed, ",");
+        var idx1: usize = 0;
+        while (splits1.next()) |s1| {
+            var idx2: usize = 0;
+            var splits2 = std.mem.tokenize(u8, s1, "-");
+            while (splits2.next()) |s2| {
+                const num = try std.fmt.parseInt(u32, s2, 10);
+
+                entry[idx1][idx2] = num;
+
+                idx2 += 1;
+            }
+
+            idx1 += 1;
+        }
+
+        try entries.append(entry);
+    }
+
+    return entries;
+}

src/main.zig

@@ -4,7 +4,8 @@ const aoc = @import("aoc.zig");
 const days = .{
     //@import("days/day1.zig"),
     //@import("days/day2.zig"),
-    @import("days/day3.zig"),
+    //@import("days/day3.zig"),
+    @import("days/day4.zig"),
 };
 
 pub fn main() !void {