Day4 - Puzzle 1

day4/example

@@ -0,0 +1,6 @@
+2-4,6-8
+2-3,4-5
+5-7,7-9
+2-8,3-7
+6-6,4-6
+2-6,4-8

day4/puzzle1.zig

@@ -0,0 +1,71 @@
+const std = @import("std");
+
+const mem = std.mem;
+const fmt = std.fmt;
+
+const input = @embedFile("input");
+
+pub fn main() !void {
+    var count: usize = 0;
+    // Iterate through the lines
+    var lines = mem.split(u8, input, "\n");
+    while (lines.next()) |line| {
+        // If line is empty, ignore
+        if (line.len == 0) continue;
+
+        var limits: [2][2]usize = undefined;
+
+        //std.debug.print("{s}\n", .{line});
+
+        // Which elf
+        var elf: usize = 0;
+        // Which limit
+        var limit: usize = 0;
+        // Start of slice
+        var start: usize = 0;
+
+        for (line) |char, index| {
+            if (char == '-') {
+
+                const number = fmt.parseInt(usize, line[start..index], 10) catch 0;
+                //std.debug.print("{}\n", .{number});
+                limits[elf][limit] = number;
+                start = index + 1;
+                limit += 1;
+
+                // 10-20,30-40
+                //    ^
+
+            }
+            if (char == ',') {
+
+                const number = fmt.parseInt(usize, line[start..index], 10) catch 0;
+                //std.debug.print("{}\n", .{number});
+                limits[elf][limit] = number;
+                start = index + 1;
+                elf += 1;
+                limit = 0;
+
+                // 10-20,30-40
+                //       ^
+
+            }
+            if (index == line.len - 1) {
+
+                const number = fmt.parseInt(usize, line[start..], 10) catch 0;
+                //std.debug.print("{}\n", .{number});
+                limits[elf][limit] = number;
+
+            }
+        }
+
+        // Check if they overlap
+
+        if ((limits[0][0] <= limits[1][0] and limits[0][1] >= limits[1][1]) or
+            (limits[1][0] <= limits[0][0] and limits[1][1] >= limits[0][1])) {
+           count += 1;
+        }
+    }
+
+    std.debug.print("{}\n", .{count});
+}