1 files changed, 88 insertions, 0 deletions

diff --git a/2024/24/day24a.cpp b/2024/24/day24a.cpp
new file mode 100644
index 0000000..231b206
--- /dev/null
+++ b/2024/24/day24a.cpp
@@ -0,0 +1,88 @@
+/* Use clean.sh on the input first */
+
+#include <algorithm>
+#include <cstdint>
+#include <iostream>
+#include <map>
+#include <queue>
+#include <ranges>
+#include <set>
+#include <sstream>
+#include <string>
+#include <string_view>
+#include <vector>
+using namespace std;
+
+int8_t state[36*36*36];
+
+int d(char x) { return x >= 'a' && x <= 'z' ? x-'a' : 26+x-'0'; }
+int index(char a, char b, char c) { return d(c) + 36 * (d(b) + 36 * d(a)); }
+int z(int i) { return index('z', (i/10)+'0', (i%10)+'0'); }
+
+enum class Op { AND, OR, XOR };
+
+class Gate {
+public:
+        int x, y, z;
+        Op op;
+
+        bool ready() const {
+                return state[x] != -1 && state[y] != -1;
+        }
+
+        bool operate() const { /* Returns true if the operation flips a bit */
+                auto oldstate = state[z];
+                switch (op) {
+                case Op::AND:
+                        state[z] = state[x] & state[y];
+                        break;
+                case Op::OR:
+                        state[z] = state[x] | state[y];
+                        break;
+                case Op::XOR:
+                        state[z] = state[x] ^ state[y];
+                        break;
+                }
+                return oldstate != state[z];
+        }
+};
+
+Op make_op(char c) {
+        switch (c) {
+        case '&': return Op::AND;
+        case '|': return Op::OR;
+        default: return Op::XOR;
+        }
+}
+
+int main() {
+        vector<Gate> gates;
+        fill(state, state + 36*36*36, -1);
+        string line;
+
+        while (getline(cin, line) && line != "")
+                state[index(line[0], line[1], line[2])] = line[5]-'0';
+
+        while (getline(cin, line))
+                gates.push_back(Gate {
+                        .x = index(line[0], line[1], line[2]),
+                        .y = index(line[6], line[7], line[8]),
+                        .z = index(line[13], line[14], line[15]),
+                        .op = make_op(line[4])
+                });
+
+        for (bool flag = true; flag; ) {
+                flag = false;
+                for (auto g : gates)
+                        if (g.ready())
+                                flag = flag || g.operate();
+        }
+
+        int64_t result = 0;
+        for (int64_t i = 0, j = 1; state[z(i)] != -1; i++, j *= 2)
+                result += (int64_t)state[z(i)] * j;
+
+        cout << result << endl;
+
+        return 0;
+}