2 files changed, 191 insertions, 1 deletions

diff --git a/makefile b/makefile
index 298d71e..e9394b6 100644
--- a/makefile
+++ b/makefile
@@ -5,7 +5,8 @@ all: bin/day01 \
          bin/day03 \
          bin/day04 \
          bin/day05 \
-         bin/day06
+         bin/day06 \
+         bin/day07
 
 bin:
         mkdir $@
diff --git a/src/day07.cpp b/src/day07.cpp
new file mode 100644
index 0000000..1f44ac5
--- /dev/null
+++ b/src/day07.cpp
@@ -0,0 +1,189 @@
+#include <algorithm>
+#include <cassert>
+#include <fstream>
+#include <iostream>
+#include <map>
+#include <sstream>
+#include <tuple>
+#include <vector>
+using namespace std;
+
+enum kind_type {
+        five_kind,
+        four_kind,
+        full_house_kind,
+        three_kind,
+        two_pair_kind,
+        one_pair_kind,
+        high_card_kind
+};
+
+kind_type
+kind1(string hand)
+{
+        map<char, size_t> mapping{};
+
+        for ( auto chr: hand ) {
+                ++mapping[chr];
+        }
+
+        sort(hand.begin(), hand.end());
+        hand.erase(unique(hand.begin(), hand.end()), hand.end());
+
+        if ( mapping.size() == 1 ) {
+                return five_kind;
+        }
+        if ( mapping.size() == 2 ) {
+                if ( mapping[hand[0]] == 4 || mapping[hand[1]] == 4 ) {
+                        return four_kind;
+                }
+                return full_house_kind;
+        }
+        if ( mapping.size() == 3 ) {
+                if ( mapping[hand[0]] == 3 || mapping[hand[1]] == 3 || mapping[hand[2]] == 3 ) {
+                        return three_kind;
+                }
+                return two_pair_kind;
+        }
+        if ( mapping.size() == 4 ) {
+                return one_pair_kind;
+        }
+
+        return high_card_kind;
+}
+
+kind_type
+kind2(const string& hand)
+{
+        map<char, size_t> mapping{};
+
+        for ( auto chr: hand ) {
+                ++mapping[chr];
+        }
+
+        auto joker_amount = mapping['J'];
+        mapping.erase('J');
+
+        vector<size_t> amounts{};
+        amounts.reserve(mapping.size());
+        for ( const auto& entry: mapping ) {
+                amounts.emplace_back(entry.second);
+        }
+
+        sort(amounts.begin(), amounts.end(), greater<>());
+        if ( amounts.empty() ) {
+                amounts.emplace_back(joker_amount);
+        }
+        else {
+                amounts[0] += joker_amount;
+        }
+
+        if ( amounts[0] == 5 ) {
+                return five_kind;
+        }
+        if ( amounts[0] == 4 ) {
+                return four_kind;
+        }
+        if ( amounts[0] == 3 and amounts[1] == 2 ) {
+                return full_house_kind;
+        }
+        if ( amounts[0] == 3 ) {
+                return three_kind;
+        }
+        if ( amounts[0] == 2 && amounts[1] == 2 ) {
+                return two_pair_kind;
+        }
+        if ( amounts[0] == 2 ) {
+                return one_pair_kind;
+        }
+
+        return high_card_kind;
+}
+
+void
+solve(const function<kind_type(string)>& kind, map<char, int> weights)
+{
+        fstream                                input{ "data/day07.txt" };
+        vector<tuple<string, kind_type, long>> values{};
+
+        string hand;
+        long   bid = 0;
+        while ( input >> hand >> bid ) {
+                values.emplace_back(hand, kind(hand), bid);
+        }
+
+        sort(values.begin(), values.end(), [&](const tuple<string, kind_type, long>& first, const tuple<string, kind_type, long>& second) {
+                const auto& first_hand  = get<0>(first);
+                const auto& second_hand = get<0>(second);
+
+                auto first_kind  = get<1>(first);
+                auto second_kind = get<1>(second);
+
+                if ( first_kind == second_kind ) {
+                        for ( size_t idx = 0; idx != 5; ++idx ) {
+                                const auto first_weight  = weights[first_hand[idx]];
+                                const auto second_weight = weights[second_hand[idx]];
+
+                                if ( first_weight != second_weight ) {
+                                        return first_weight < second_weight;
+                                }
+                        }
+                }
+                return first_kind > second_kind;
+        });
+
+        long total = 0;
+        long rank  = 1;
+        for ( const auto& value: values ) {
+                total += rank * get<2>(value);
+                ++rank;
+        }
+        cout << total << endl;
+}
+
+int
+main()
+{
+        assert(kind1("AAAAA") == five_kind);
+        assert(kind1("AA8AA") == four_kind);
+        assert(kind1("23332") == full_house_kind);
+        assert(kind1("TTT98") == three_kind);
+        assert(kind1("23432") == two_pair_kind);
+        assert(kind1("A23A4") == one_pair_kind);
+        assert(kind1("23456") == high_card_kind);
+
+        map<char, int> weights1 = {
+                { '2', 2 },
+                { '3', 3 },
+                { '4', 4 },
+                { '5', 5 },
+                { '6', 6 },
+                { '7', 7 },
+                { '8', 8 },
+                { '9', 9 },
+                { 'T', 10 },
+                { 'J', 11 },
+                { 'Q', 12 },
+                { 'K', 13 },
+                { 'A', 14 },
+        };
+
+        map<char, int> weights2 = {
+                { 'J', 1 },
+                { '2', 2 },
+                { '3', 3 },
+                { '4', 4 },
+                { '5', 5 },
+                { '6', 6 },
+                { '7', 7 },
+                { '8', 8 },
+                { '9', 9 },
+                { 'T', 10 },
+                { 'Q', 11 },
+                { 'K', 12 },
+                { 'A', 13 },
+        };
+
+        solve(kind1, weights1);
+        solve(kind2, weights2);
+}