extract parsing code for day2 + tidy

2020/zig/src/day02.zig

@@ -1,44 +1,60 @@
 const std = @import("std");
-const Allocator = std.mem.Allocator;
-const List = std.ArrayList;
-const Map = std.AutoHashMap;
-const StrMap = std.StringHashMap;
-const BitSet = std.DynamicBitSet;
-const Str = []const u8;
+const gpa = @import("util.zig").gpa;
+const ArrayList = std.ArrayList;
+const tokenize = std.mem.tokenize;
+const parseInt = std.fmt.parseInt;
+const print = std.debug.print;
 
-const util = @import("util.zig");
-const gpa = util.gpa;
+const data = @embedFile("input");
 
-const data = @embedFile("../data/day02.txt");
+const Rule = struct {
+    a: u8, b: u8, char: u8, password: []const u8
+};
 
 pub fn main() !void {
-    
+    const rules = try parse();
+    print("Part 1: {d}\n", .{part1(rules)});
+    print("Part 2: {d}\n", .{part2(rules)});
 }
 
-// Useful stdlib functions
-const tokenize = std.mem.tokenize;
-const split = std.mem.split;
-const indexOf = std.mem.indexOfScalar;
-const indexOfAny = std.mem.indexOfAny;
-const indexOfStr = std.mem.indexOfPosLinear;
-const lastIndexOf = std.mem.lastIndexOfScalar;
-const lastIndexOfAny = std.mem.lastIndexOfAny;
-const lastIndexOfStr = std.mem.lastIndexOfLinear;
-const trim = std.mem.trim;
-const sliceMin = std.mem.min;
-const sliceMax = std.mem.max;
 
-const parseInt = std.fmt.parseInt;
-const parseFloat = std.fmt.parseFloat;
+fn parse() ![]Rule {
+    var it = tokenize(u8, data, "\n");
+    var rules = ArrayList(Rule).init(gpa);
+    while (it.next()) |line| {
+        var line_it = tokenize(u8, line, ": -");
+        const a = try parseInt(u8, line_it.next().?, 10);
+        const b = try parseInt(u8, line_it.next().?, 10);
+        const char = line_it.next().?[0];
+        const password = line_it.next().?;
+        try rules.append(Rule{.a = a, .b = b, .char = char, .password = password});
+    }
+    return rules.toOwnedSlice();
+}
 
-const min = std.math.min;
-const min3 = std.math.min3;
-const max = std.math.max;
-const max3 = std.math.max3;
+fn part1(rules: []Rule) !u16 {
+    var valid_pw_count: u16 = 0;
+    for (rules) |rule| {
+        var count: u8 = 0;
+        for (rule.password) |password_char| {
+            if (rule.char == password_char)
+                count += 1; 
+        }
 
-const print = std.debug.print;
-const assert = std.debug.assert;
+        if (rule.a <= count and count <= rule.b)
+            valid_pw_count += 1;
+    }
+    return valid_pw_count;
+}
 
-const sort = std.sort.sort;
-const asc = std.sort.asc;
-const desc = std.sort.desc;
+fn part2(rules: []Rule) !u16 {
+    var valid_pw_count: u16 = 0;
+    for (rules) |rule| {
+        const a_match = rule.password[rule.a-1] == rule.char;
+        const b_match = rule.password[rule.b-1] == rule.char;
+        // No xor in zig?
+        if (a_match and !b_match or !a_match and b_match)
+            valid_pw_count += 1;
+    }
+    return valid_pw_count;
+}