Day 4 in zig

zig/4/part1.zig

@@ -0,0 +1,38 @@
+const std = @import("std");
+
+const Pair = struct {
+    low: i32 = 0,
+    high: i32 = 0,
+    fn fullyOverlaps(self: *Pair, other: *Pair) bool {
+        return (self.low <= other.low and self.high >= other.high) or (self.low >= other.low and self.high <= other.high);
+    }
+};
+
+fn parsei32Guaranteed(str: []const u8) i32 {
+    return std.fmt.parseInt(i32, str, 10) catch unreachable;
+}
+
+pub fn main() !void {
+    var file = try std.fs.cwd().openFile("input.txt", .{});
+    defer file.close();
+
+    var a = std.io.bufferedReader(file.reader());
+    var readerStream = a.reader();
+
+    var count: i32 = 0;
+    var buf: [32]u8 = undefined;
+    while (try readerStream.readUntilDelimiterOrEof(&buf, '\n')) |line| {
+        var pairStrings = std.mem.split(u8, line, ",");
+        var pairs = [_]Pair{ .{}, .{} };
+        for (pairs) |*pair| {
+            var elements = std.mem.split(u8, pairStrings.next().?, "-");
+            pair.low = parsei32Guaranteed(elements.next().?);
+            pair.high = parsei32Guaranteed(elements.next().?);
+        }
+        if (pairs[0].fullyOverlaps(&pairs[1])) {
+            count += 1;
+        }
+    }
+
+    std.debug.print("{d}\n", .{count});
+}

zig/4/part2.zig

@@ -0,0 +1,41 @@
+const std = @import("std");
+
+const Pair = struct {
+    low: i32 = 0,
+    high: i32 = 0,
+    fn fullyOverlaps(self: *Pair, other: *Pair) bool {
+        return (self.low <= other.low and self.high >= other.high) or (self.low >= other.low and self.high <= other.high);
+    }
+    fn partiallyOverlaps(self: *Pair, other: *Pair) bool {
+        return (self.low <= other.high and self.high >= other.low);
+    }
+};
+
+fn parsei32Guaranteed(str: []const u8) i32 {
+    return std.fmt.parseInt(i32, str, 10) catch unreachable;
+}
+
+pub fn main() !void {
+    var file = try std.fs.cwd().openFile("input.txt", .{});
+    defer file.close();
+
+    var a = std.io.bufferedReader(file.reader());
+    var readerStream = a.reader();
+
+    var count: i32 = 0;
+    var buf: [32]u8 = undefined;
+    while (try readerStream.readUntilDelimiterOrEof(&buf, '\n')) |line| {
+        var pairStrings = std.mem.split(u8, line, ",");
+        var pairs = [_]Pair{ .{}, .{} };
+        for (pairs) |*pair| {
+            var elements = std.mem.split(u8, pairStrings.next().?, "-");
+            pair.low = parsei32Guaranteed(elements.next().?);
+            pair.high = parsei32Guaranteed(elements.next().?);
+        }
+        if (pairs[0].partiallyOverlaps(&pairs[1])) {
+            count += 1;
+        }
+    }
+
+    std.debug.print("{d}\n", .{count});
+}