day 5

day5_p1.zig

@@ -0,0 +1,56 @@
+const std = @import("std");
+
+pub fn main() !void {
+    const stdin = std.io.getStdIn();
+    var buf_io = std.io.bufferedReader(stdin.reader());
+    var reader = buf_io.reader();
+
+    var buf = [_]u8{0} ** 1024;
+    var total: usize = 0;
+    while (try reader.readUntilDelimiterOrEof(&buf, '\n')) |line| {
+        const trimmed = std.mem.trim(u8, line, " \n\r\x00");
+        if (is_nice(trimmed)) {
+            total += 1;
+        }
+    }
+
+    std.debug.print("{}", .{total});
+}
+
+fn is_nice(s: []const u8) bool {
+    var vowels: u16 = 0;
+    var has_consecutive: bool = false;
+
+    var last_letter: u8 = '_';
+    for (s) |c| {
+        if (c == last_letter) {
+            has_consecutive = true;
+        }
+        switch (c) {
+            'a', 'e', 'i', 'o', 'u' => {
+                vowels += 1;
+            },
+            else => {
+                // Check for forbidden sequences
+                if ((last_letter == 'a' and c == 'b') or
+                    (last_letter == 'c' and c == 'd') or
+                    (last_letter == 'p' and c == 'q') or
+                    (last_letter == 'x' and c == 'y'))
+                {
+                    return false;
+                }
+            },
+        }
+        last_letter = c;
+    }
+
+    return vowels > 2 and has_consecutive;
+}
+
+test "day-tests" {
+    try std.testing.expectEqual(is_nice("ugknbfddgicrmopn"), true);
+    try std.testing.expectEqual(is_nice("aaa"), true);
+    try std.testing.expectEqual(is_nice("jchzalrnumimnmhp"), false);
+    try std.testing.expectEqual(is_nice("haegwjzuvuyypxyu"), false);
+    try std.testing.expectEqual(is_nice("dvszwmarrgswjxmb"), false);
+}

day5_p2.zig

@@ -0,0 +1,50 @@
+const std = @import("std");
+
+pub fn main() !void {
+    const stdin = std.io.getStdIn();
+    var buf_io = std.io.bufferedReader(stdin.reader());
+    var reader = buf_io.reader();
+
+    var buf = [_]u8{0} ** 1024;
+    var total: usize = 0;
+    while (try reader.readUntilDelimiterOrEof(&buf, '\n')) |line| {
+        const trimmed = std.mem.trim(u8, line, " \n\r\x00");
+        if (is_nice(trimmed)) {
+            total += 1;
+        }
+    }
+
+    std.debug.print("{}", .{total});
+}
+
+fn is_nice(s: []const u8) bool {
+    var has_repeating = false;
+    var has_semi_consecutive: bool = false;
+
+    var last_letter: u8 = '_';
+    var letter_even_before: u8 = '_';
+    for (s, 0..) |c, i| {
+        if (c == letter_even_before) {
+            has_semi_consecutive = true;
+        }
+        if (i > 1 and std.mem.indexOf(u8, s, &[2]u8{ last_letter, c }).? < i - 2) {
+            has_repeating = true;
+        }
+        letter_even_before = last_letter;
+        last_letter = c;
+    }
+
+    return has_repeating and has_semi_consecutive;
+}
+
+test "day-tests" {
+    try std.testing.expectEqual(true, is_nice("qjhvhtzxzqqjkmpb"));
+    try std.testing.expectEqual(true, is_nice("xxyxx"));
+    try std.testing.expectEqual(false, is_nice("uurcxstgmygtbstg"));
+    try std.testing.expectEqual(false, is_nice("ieodomkazucvgmuy"));
+}
+
+test "custom-test" {
+    try std.testing.expectEqual(false, is_nice("aaa"));
+    try std.testing.expectEqual(true, is_nice("aaaa"));
+}