day x

day5/day5_part1.zig

@@ -0,0 +1,133 @@
+const std = @import("std");
+const in = @embedFile("in");
+
+fn array_includes(comptime T: type, haystack: []T, needle: T) bool {
+    for (haystack) |item| {
+        if (item == needle) {
+            return true;
+        }
+    }
+    return false;
+}
+
+pub fn main() !void {
+    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    const ally = gpa.allocator();
+    defer _ = gpa.deinit();
+
+    var lines = std.ArrayList(std.ArrayList(u32)).init(ally);
+    var incorrect_line_idxs = std.ArrayList(u32).init(ally);
+    defer {
+        for (lines.items) |*line| {
+            line.deinit();
+        }
+        lines.deinit();
+        incorrect_line_idxs.deinit();
+    }
+
+    var dependencies = std.AutoHashMap(u32, std.ArrayList(u32)).init(ally);
+    defer {
+        var iter = dependencies.iterator();
+        while (iter.next()) |entry| {
+            entry.value_ptr.deinit();
+        }
+        dependencies.deinit();
+    }
+
+    var in_lines = std.mem.tokenize(u8, in, "\n");
+    var parsing_dependencies = false;
+    var i: u32 = 0;
+    while (in_lines.next()) |line| {
+        if (std.mem.indexOf(u8, line, "|")) |_| {
+            parsing_dependencies = true;
+        } else {
+            parsing_dependencies = false;
+        }
+
+        if (line.len > 0 and parsing_dependencies) {
+            var dependance = std.mem.split(u8, line, "|");
+            const num1 = try std.fmt.parseInt(u32, dependance.next().?, 10);
+            const num2 = try std.fmt.parseInt(u32, dependance.next().?, 10);
+
+            var entry = try dependencies.getOrPut(num2);
+            if (!entry.found_existing) {
+                entry.value_ptr.* = std.ArrayList(u32).init(ally);
+            }
+
+            try entry.value_ptr.append(num1);
+        } else if (line.len > 0 and !parsing_dependencies) {
+            var ints = std.mem.split(u8, line, ",");
+            var intLine = std.ArrayList(u32).init(ally);
+            while (ints.next()) |int| {
+                try intLine.append(try std.fmt.parseInt(u32, int, 10));
+            }
+            try lines.append(intLine);
+        }
+        i += 1;
+    }
+
+    // Part 1
+    var middle_page_number_sum: u32 = 0;
+    for (lines.items, 0..) |line, lidx| {
+        var is_correct = true;
+        outer: for (line.items, 0..) |num1, j| {
+            for (line.items[0..j]) |num2| {
+                const deps = dependencies.get(num1);
+
+                if (deps == null) {
+                    is_correct = false;
+                    break :outer;
+                }
+
+                var found = false;
+                for (deps.?.items) |dep| {
+                    if (dep == num2) {
+                        found = true;
+                        break;
+                    }
+                }
+                if (!found) {
+                    is_correct = false;
+                    break :outer;
+                }
+            }
+        }
+
+        if (is_correct) {
+            middle_page_number_sum += line.items[line.items.len / 2];
+        } else {
+            try incorrect_line_idxs.append(@intCast(lidx));
+        }
+    }
+    std.debug.print("Part1: {}\n", .{middle_page_number_sum});
+
+    // Part 2
+    middle_page_number_sum = 0;
+    for (incorrect_line_idxs.items) |idx| {
+        const line = lines.items[idx];
+        var fixed_line = std.ArrayList(u32).init(ally);
+        defer fixed_line.deinit();
+
+        for (line.items) |num| {
+            const deps = dependencies.get(num);
+
+            if (deps == null) {
+                try fixed_line.insert(0, num);
+                continue;
+            }
+
+            var j: usize = 0;
+            for (fixed_line.items) |comparison_num| {
+                if (array_includes(u32, deps.?.items, comparison_num)) {
+                    j += 1;
+                    continue;
+                }
+            }
+            try fixed_line.insert(j, num);
+        }
+
+        middle_page_number_sum += fixed_line.items[fixed_line.items.len / 2];
+    }
+
+    std.debug.print("Part 2: {}\n", .{middle_page_number_sum});
+}

day5/test

@@ -0,0 +1,28 @@
+47|53
+97|13
+97|61
+97|47
+75|29
+61|13
+75|53
+29|13
+97|29
+53|29
+61|53
+97|53
+61|29
+47|13
+75|47
+97|75
+47|61
+75|61
+47|29
+75|13
+53|13
+
+75,47,61,53,29
+97,61,53,29,13
+75,29,13
+75,97,47,61,53
+61,13,29
+97,13,75,29,47