refactored to make part 2 easier

day03-easy/src/main.zig

@@ -1,20 +1,27 @@
 const std = @import("std");
 
-fn isSymbol(char: u8) bool {
-    return switch (char) {
-        '0'...'9' => false,
-        '.' => false,
-        else => true,
+const Char = enum(u4) {
+    Zero = 0,
+    One = 1,
+    Two = 2,
+    Three = 3,
+    Four = 4,
+    Five = 5,
+    Six = 6,
+    Seven = 7,
+    Eight = 8,
+    Nine = 9,
+    Dot = 12,
+    Symbol = 13,
 };
-}
 
 const CharInfo = struct {
-    adjacents: [8]u8,
-    this: u8,
+    adjacents: [8]Char,
+    this: Char,
 
     fn isAdjacentToSymbol(self: *const CharInfo) bool {
         for (0..8) |i| {
-            if (isSymbol(self.adjacents[i])) {
+            if (self.adjacents[i] == .Symbol) {
                 return true;
             }
         }
@@ -28,7 +35,7 @@ const State = struct {
     is_adjacent_to_symbol: bool = false,
 
     fn addDigit(self: *State, char_info: CharInfo) void {
-        self.number = self.number * 10 + (char_info.this - '0');
+        self.number = self.number * 10 + @intFromEnum(char_info.this);
         self.is_adjacent_to_symbol = self.is_adjacent_to_symbol or char_info.isAdjacentToSymbol();
     }
 };
@@ -42,10 +49,10 @@ fn solve(engine: [][]const CharInfo) u32 {
         for (line) |char_info| {
             //std.debug.print("handling: {s}({s})\n", .{ [_]u8{char_info.this}, char_info.adjacents });
             switch (char_info.this) {
-                '0'...'9' => {
+                .Zero, .One, .Two, .Three, .Four, .Five, .Six, .Seven, .Eight, .Nine => {
                     current_state.addDigit(char_info);
                 },
-                else => {
+                .Dot, .Symbol => {
                     if (current_state.is_adjacent_to_symbol) {
                         //std.debug.print("adding: {d}\n", .{current_state.number});
                         result += current_state.number;
@@ -67,21 +74,21 @@ fn solve(engine: [][]const CharInfo) u32 {
     return result;
 }
 
-fn charLinesToCharInfoLines(allocator: std.mem.Allocator, char_lines: [][]const u8) ![][]const CharInfo {
+fn charLinesToCharInfoLines(allocator: std.mem.Allocator, char_lines: [][]const Char) ![][]const CharInfo {
     var char_info_lines = try allocator.alloc([]CharInfo, char_lines.len);
     for (0..char_lines.len) |i| {
         const char_line = char_lines[i];
         var char_info_line = try allocator.alloc(CharInfo, char_line.len);
         for (0..char_line.len) |j| {
             char_info_line[j] = CharInfo{ .this = char_line[j], .adjacents = .{
-                if (i > 0 and j > 0) char_lines[i - 1][j - 1] else '.',
-                if (i > 0) char_lines[i - 1][j] else '.',
-                if (i > 0 and j + 1 < char_line.len) char_lines[i - 1][j + 1] else '.',
-                if (j > 0) char_line[j - 1] else '.',
-                if (j + 1 < char_line.len) char_line[j + 1] else '.',
-                if (i + 1 < char_lines.len and j > 0) char_lines[i + 1][j - 1] else '.',
-                if (i + 1 < char_lines.len) char_lines[i + 1][j] else '.',
-                if (i + 1 < char_lines.len and j + 1 < char_line.len) char_lines[i + 1][j + 1] else '.',
+                if (i > 0 and j > 0) char_lines[i - 1][j - 1] else .Dot,
+                if (i > 0) char_lines[i - 1][j] else .Dot,
+                if (i > 0 and j + 1 < char_line.len) char_lines[i - 1][j + 1] else .Dot,
+                if (j > 0) char_line[j - 1] else .Dot,
+                if (j + 1 < char_line.len) char_line[j + 1] else .Dot,
+                if (i + 1 < char_lines.len and j > 0) char_lines[i + 1][j - 1] else .Dot,
+                if (i + 1 < char_lines.len) char_lines[i + 1][j] else .Dot,
+                if (i + 1 < char_lines.len and j + 1 < char_line.len) char_lines[i + 1][j + 1] else .Dot,
             } };
         }
 
@@ -91,11 +98,18 @@ fn charLinesToCharInfoLines(allocator: std.mem.Allocator, char_lines: [][]const
     return char_info_lines;
 }
 
-fn readInput(allocator: std.mem.Allocator, reader: anytype) ![][]const u8 {
-    var lines = std.ArrayList([]u8).init(allocator);
+fn readInput(allocator: std.mem.Allocator, reader: anytype) ![][]const Char {
+    var lines = std.ArrayList([]Char).init(allocator);
     var line_buffer: [1000]u8 = undefined;
     while (try reader.readUntilDelimiterOrEof(&line_buffer, '\n')) |line_ref| {
-        const line = try allocator.dupe(u8, line_ref);
+        var line = try allocator.alloc(Char, line_ref.len);
+        for (line_ref, line) |raw_char, *char| {
+            char.* = switch (raw_char) {
+                '0'...'9' => @enumFromInt(raw_char - '0'),
+                '.' => .Dot,
+                else => .Symbol,
+            };
+        }
         try lines.append(line);
     }