day01

1 files changed, 90 insertions, 0 deletions

diff --git a/day01/solution.zig b/day01/solution.zig
new file mode 100644
index 0000000..6d15175
--- /dev/null
+++ b/day01/solution.zig
@@ -0,0 +1,90 @@
+const std = @import("std");
+const print = std.debug.print;
+const assert = std.debug.assert;
+const mem = std.mem;
+
+const fin = mem.trim(u8, @embedFile("./input.txt"), &std.ascii.whitespace);
+
+const digits_p1 = [_]u8{
+    '0',
+    '1',
+    '2',
+    '3',
+    '4',
+    '5',
+    '6',
+    '7',
+    '8',
+    '9',
+};
+
+const digits_p2 = [_][]const u8{
+    "0", "zero",
+    "1", "one",
+    "2", "two",
+    "3", "three",
+    "4", "four",
+    "5", "five",
+    "6", "six",
+    "7", "seven",
+    "8", "eight",
+    "9", "nine",
+};
+
+pub fn part1(comptime T: type, input: T) void {
+    var ans: u64 = 0;
+    var it = input;
+    while (it.next()) |line| {
+        const first = line[mem.indexOfAny(u8, line, &digits_p1) orelse continue] - '0';
+        const last = line[mem.lastIndexOfAny(u8, line, &digits_p1) orelse continue] - '0';
+        const n = 10 * first + last;
+
+        ans += n;
+    }
+
+    print("{d}\n", .{ans});
+}
+
+pub fn part2(comptime T: type, input: T) void {
+    var ans: u64 = 0;
+    var it = input;
+    while (it.next()) |line| {
+        var first: u64 = 0;
+        var last: u64 = 0;
+        var first_idx: i64 = 10000000;
+        var last_idx: i64 = -1;
+
+        for (digits_p2, 0..) |d, i| {
+            if (mem.indexOf(u8, line, d)) |t| {
+                const fi: i64 = @bitCast(t);
+                if (fi < first_idx) {
+                    first_idx = fi;
+                    first = i / 2;
+                }
+            }
+            if (mem.lastIndexOf(u8, line, d)) |t| {
+                const li: i64 = @bitCast(t);
+                if (li > last_idx) {
+                    last_idx = li;
+                    last = i / 2;
+                }
+            }
+        }
+        const n = 10 * first + last;
+
+        ans += n;
+    }
+
+    print("{d}\n", .{ans});
+}
+
+pub fn main() !void {
+    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    defer _ = gpa.deinit();
+    var alloc = gpa.allocator();
+    _ = alloc;
+
+    const input = mem.splitScalar(u8, fin, '\n');
+    part1(@TypeOf(input), input);
+    part2(@TypeOf(input), input);
+}