Day 17 2024 - this was fun

1 files changed, 102 insertions, 0 deletions

diff --git a/2024/17/day17b-bruteforce.cpp b/2024/17/day17b-bruteforce.cpp
new file mode 100644
index 0000000..a400d5c
--- /dev/null
+++ b/2024/17/day17b-bruteforce.cpp
@@ -0,0 +1,102 @@
+#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;
+
+class CPU {
+public:
+        CPU(uint64_t a, uint64_t b, uint64_t c) : A{a}, B{b}, C{c} {}
+
+        bool process(const vector<uint64_t>& v) {
+                unsigned j = 0;
+                for (unsigned ip = 0; ip < v.size() && j <= v.size(); ) {
+                        switch (v[ip]) {
+                        case 0:
+                                A >>= combo(v[ip+1]);
+                                ip += 2;
+                                break;
+                        case 1:
+                                B ^= v[ip+1];
+                                ip += 2;
+                                break;
+                        case 2:
+                                B = combo(v[ip+1]) % 8;
+                                ip += 2;
+                                break;
+                        case 3:
+                                ip = A == 0 ? ip+2 : v[ip+1];
+                                break;
+                        case 4:
+                                B ^= C;
+                                ip += 2;
+                                break;
+                        case 5:
+                                if (j == v.size() || v[j] != combo(v[ip+1])%8)
+                                        return false;
+                                j++;
+                                ip += 2;
+                                break;
+                        case 6:
+                                B = A >> combo(v[ip+1]);
+                                ip += 2;
+                                break;
+                        case 7:
+                                C = A >> combo(v[ip+1]);
+                                ip += 2;
+                                break;
+                        default:
+                                cout << "Error! Operator " << v[ip] << endl;
+                                exit(1);
+                        }
+                }
+                return j == v.size();
+        }
+
+        void setreg(uint64_t a, uint64_t b, uint64_t c) {
+                A = a;
+                B = b;
+                C = c;
+        }
+private:
+        uint64_t A, B, C;
+
+        uint64_t& reg(uint64_t i) {
+                return i == 0 ? A : (i == 1 ? B : C);
+        }
+
+        uint64_t combo(uint64_t i) {
+                return i <= 3 ? i : reg(i-4);
+        }
+};
+
+int main() {
+        uint64_t a, b, c;
+        cin >> a >> b >> c;
+        CPU cpu(a, b, c);
+
+        vector<uint64_t> instructions;
+        while (cin >> a)
+                instructions.push_back(a);
+
+        const uint64_t M = 10000000000;
+        const uint64_t N = 100000000000;
+        for (a = M; a < N; a++) {
+if (a % 1000000 == 0)
+cout << "tring " << a << endl;
+                cpu.setreg(a, 0, 0);
+                if (cpu.process(instructions)) {
+                        cout << "Found it: " << a << endl;
+                        return 0;
+                }
+        }
+        cout << "Not found for A < " << N << endl;
+        return 0;
+}