day01: part2

src/day01.zig

@@ -4,9 +4,12 @@ const util = @import("util.zig");
 pub fn main() !void {
     const input = @embedFile("data/day01.txt");
     const sln = try solve(input);
-    std.debug.print("Part 1: {d}", .{sln});
+    std.debug.print("Solution: {d}", .{sln});
 }
 
+const numbers = [_][]const u8{ "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" };
+const zero = @as(u8, '0');
+
 fn solve(input: []const u8) !u32 {
     var sum: u32 = 0;
 
@@ -18,17 +21,27 @@ fn solve(input: []const u8) !u32 {
 
         var first: u8 = 0;
         var last: u8 = 0;
-        for (line) |char| {
-            if (char < '0' or char > '9') {
-                continue;
+
+        for (0..line.len) |offset| {
+            var n: u8 = 0; // ascii value
+            if (line[offset] >= '0' and line[offset] <= '9') {
+                n = line[offset];
+            } else {
+                inline for (numbers, 0..) |word, value| {
+                    if (std.mem.startsWith(u8, line[offset..], word)) {
+                        n = value + zero;
+                        break;
+                    }
+                }
             }
-            if (first == 0) {
-                first = char;
+            if (n != 0) {
+                if (first == 0) {
+                    first = n;
+                }
+                last = n;
             }
-            last = char;
         }
 
-        const zero = @as(u8, '0');
         const cal_value = (first - zero) * 10 + (last - zero);
         sum += cal_value;
     }
@@ -38,11 +51,14 @@ fn solve(input: []const u8) !u32 {
 
 test "sample" {
     const input =
-        \\1abc2
-        \\pqr3stu8vwx
-        \\a1b2c3d4e5f
-        \\treb7uchet
+        \\two1nine
+        \\eightwothree
+        \\abcone2threexyz
+        \\xtwone3four
+        \\4nineeightseven2
+        \\zoneight234
+        \\7pqrstsixteen
     ;
     const sln = try solve(input);
-    try std.testing.expectEqual(@as(u32, 142), sln);
+    try std.testing.expectEqual(@as(u32, 281), sln);
 }