day7

2 files changed, 220 insertions, 0 deletions

diff --git a/day07/example.txt b/day07/example.txt
new file mode 100644
index 0000000..e3500c3
--- /dev/null
+++ b/day07/example.txt
@@ -0,0 +1,5 @@
+32T3K 765
+T55J5 684
+KK677 28
+KTJJT 220
+QQQJA 483
diff --git a/day07/solution.zig b/day07/solution.zig
new file mode 100644
index 0000000..b452dfb
--- /dev/null
+++ b/day07/solution.zig
@@ -0,0 +1,215 @@
+const std = @import("std");
+const print = std.debug.print;
+const assert = std.debug.assert;
+const ArrayList = std.ArrayList;
+const HashMap = std.HashMap;
+const mem = std.mem;
+
+const fin = mem.trim(u8, @embedFile("./input.txt"), &std.ascii.whitespace);
+var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+const allocator = gpa.allocator();
+
+const Combo = enum(u32) {
+    high,
+    pair1,
+    pair2,
+    triple,
+    full,
+    quad,
+    quint,
+};
+
+const Player = struct {
+    bid: u64,
+    hand: [5]u8,
+    combo: Combo,
+
+    fn evalHand(hand: []const u8) Combo {
+        var cardF = [_]u32{0} ** 256;
+
+        for (hand) |c| {
+            cardF[c] += 1;
+        }
+
+        var combo = Combo.high;
+        for (cardF) |f| {
+            switch (f) {
+                0, 1 => {},
+                2 => {
+                    combo = switch (combo) {
+                        .pair1 => .pair2,
+                        .triple => .full,
+                        else => .pair1,
+                    };
+                },
+                3 => combo = if (combo == Combo.pair1) .full else .triple,
+                4 => combo = .quad,
+                5 => combo = .quint,
+                else => unreachable,
+            }
+        }
+
+        return combo;
+    }
+
+    fn evalHandWithJoker(hand: []const u8) Combo {
+        var cardF = [_]u32{0} ** 256;
+        var cmax: usize = 0;
+
+        for (hand) |c| {
+            cardF[c] += 1;
+            if (c != 'J' and cardF[c] > cardF[cmax]) {
+                cmax = c;
+            }
+        }
+
+        cardF[cmax] += cardF['J'];
+
+        var combo = Combo.high;
+        for (cardF, 0..) |f, c| {
+            if (c == 'J') {
+                continue;
+            }
+            switch (f) {
+                0, 1 => {},
+                2 => {
+                    combo = switch (combo) {
+                        .pair1 => .pair2,
+                        .triple => .full,
+                        else => .pair1,
+                    };
+                },
+                3 => combo = if (combo == Combo.pair1) .full else .triple,
+                4 => combo = .quad,
+                5 => combo = .quint,
+                else => unreachable,
+            }
+        }
+
+        return combo;
+    }
+
+    pub fn init(hand: []const u8, bid: u64) Player {
+        var res: Player = undefined;
+        res.bid = bid;
+        res.combo = Player.evalHand(hand);
+        mem.copy(u8, &res.hand, hand);
+
+        return res;
+    }
+
+    pub fn initWithJoker(hand: []const u8, bid: u64) Player {
+        var res: Player = undefined;
+        res.bid = bid;
+        res.combo = Player.evalHandWithJoker(hand);
+        mem.copy(u8, &res.hand, hand);
+
+        return res;
+    }
+};
+
+fn cardValue(c: u8) u64 {
+    switch (c) {
+        '2'...'9' => return c - '0',
+        'T' => return 10,
+        'J' => return 11,
+        'Q' => return 12,
+        'K' => return 13,
+        'A' => return 14,
+        else => unreachable,
+    }
+}
+
+fn cmpCard(_: void, lhs: u8, rhs: u8) bool {
+    return cardValue(lhs) < cardValue(rhs);
+}
+
+fn playerCmp(_: void, lhs: Player, rhs: Player) bool {
+    if (lhs.combo != rhs.combo) {
+        return @intFromEnum(lhs.combo) < @intFromEnum(rhs.combo);
+    }
+
+    for (lhs.hand, rhs.hand) |l, r| {
+        if (l != r) {
+            return cmpCard(undefined, l, r);
+        }
+    }
+
+    return false;
+}
+
+fn cardValueWithJoker(c: u8) u64 {
+    switch (c) {
+        '2'...'9' => return c - '0',
+        'T' => return 10,
+        'J' => return 0,
+        'Q' => return 12,
+        'K' => return 13,
+        'A' => return 14,
+        else => unreachable,
+    }
+}
+
+fn cmpCardWithJoker(_: void, lhs: u8, rhs: u8) bool {
+    return cardValueWithJoker(lhs) < cardValueWithJoker(rhs);
+}
+
+fn playerCmpWithJoker(_: void, lhs: Player, rhs: Player) bool {
+    if (lhs.combo != rhs.combo) {
+        return @intFromEnum(lhs.combo) < @intFromEnum(rhs.combo);
+    }
+
+    for (lhs.hand, rhs.hand) |l, r| {
+        if (l != r) {
+            return cmpCardWithJoker(undefined, l, r);
+        }
+    }
+
+    return false;
+}
+
+pub fn part1(players: []Player) void {
+    var ans: u64 = 0;
+
+    mem.sort(Player, players, {}, playerCmp);
+
+    for (players, 1..) |p, rank| {
+        ans += p.bid * rank;
+    }
+
+    print("{d}\n", .{ans});
+}
+
+pub fn part2(players: []Player) void {
+    var ans: u64 = 0;
+
+    mem.sort(Player, players, {}, playerCmpWithJoker);
+
+    for (players, 1..) |p, rank| {
+        ans += p.bid * rank;
+    }
+
+    print("{d}\n", .{ans});
+}
+
+pub fn main() !void {
+    var splitLines = mem.splitScalar(u8, fin, '\n');
+    var players_pt1 = ArrayList(Player).init(allocator);
+    var players_pt2 = ArrayList(Player).init(allocator);
+    defer {
+        players_pt1.deinit();
+        players_pt2.deinit();
+    }
+
+    while (splitLines.next()) |line| {
+        var splitElem = mem.splitScalar(u8, line, ' ');
+        const hand = splitElem.next().?;
+        const bid = try std.fmt.parseInt(u64, splitElem.next().?, 10);
+
+        try players_pt1.append(Player.init(hand, bid));
+        try players_pt2.append(Player.initWithJoker(hand, bid));
+    }
+
+    part1(players_pt1.items);
+    part2(players_pt2.items);
+}