Day 7

d07/main.cxx

@@ -1,15 +1,130 @@
 #include <iostream>
-#include <fstream>
+#include <sstream>
+#include <vector>
+#include <string>
+#include <chrono>
+#include <functional>
 
 using std::cout, std::endl;
 
-int main() {
-    std::ifstream file{"../d7/input.txt"};
-    std::string line;
+constexpr const char content[] = {
+    #embed "input.txt"
+};
 
-    while (std::getline(file, line)) {
+std::vector<std::vector<uint64_t>> generate_combinations(int n, int k) {
+    std::vector<std::vector<uint64_t>> result = {};
+    std::vector<uint64_t> current(n, 0);
+
+    while (true) {
+        result.push_back(current);
+
+        int pos = n - 1;
+        while (pos >= 0 && current[pos] == k - 1) {
+            pos--;
+        }
+
+        if (pos < 0) break; 
+
+        current[pos]++;
+        for (uint64_t i = pos + 1; i < n; i++) {
+            current[i] = 0;
+        }
+    }
+
+    return result;
+}
+
+uint64_t part_1() {
+    std::istringstream input_stream(content);
+    std::string line;
+    std::vector<std::function<uint64_t(uint64_t, uint64_t)>> defined_ops = {
+        [](uint64_t x, uint64_t y) { return x + y; },  
+        [](uint64_t x, uint64_t y) { return x * y; },    
+    };
+
+    uint64_t acc{0};
+    while (std::getline(input_stream, line)) {
+        if(line.empty()) {
+            continue;
+        }
+        std::istringstream line_stream(line);
+        std::vector<uint64_t> values = {};
         
+        std::string test_string;
+        line_stream >> test_string;
+        uint64_t val;
+        while (line_stream >> val) {
+            values.push_back(val);
+        }
+
+        uint64_t test = std::stoull(test_string);
+        std::vector<std::vector<uint64_t>> op_combinations = generate_combinations(values.size() - 1, defined_ops.size());
+        
+        for(auto& op_comb : op_combinations) {
+            uint64_t result = values[0];
+            for(uint64_t i = 1; i < values.size(); i++) {
+                result = defined_ops[op_comb[i-1]](result, values[i]);
+            }
+            if(result == test) {
+                acc += test;
+                break;
+            }
+        }
     }
     
+    return acc;
+}
+
+uint64_t part_2() {
+    std::istringstream input_stream(content);
+    std::string line;
+    std::vector<std::function<uint64_t(uint64_t, uint64_t)>> defined_ops = {
+        [](uint64_t x, uint64_t y) { return x + y; },  
+        [](uint64_t x, uint64_t y) { return x * y; },    
+        [](uint64_t x, uint64_t y) { return std::stoull(std::to_string(x) + std::to_string(y)); },
+    };
+
+    uint64_t acc{0};
+    while (std::getline(input_stream, line)) {
+        if(line.empty()) {
+            continue;
+        }
+        std::istringstream line_stream(line);
+        std::vector<uint64_t> values = {};
+        
+        std::string test_string;
+        line_stream >> test_string;
+        uint64_t val;
+        while (line_stream >> val) {
+            values.push_back(val);
+        }
+
+        uint64_t test = std::stoull(test_string);
+        std::vector<std::vector<uint64_t>> op_combinations = generate_combinations(values.size() - 1, defined_ops.size());
+        
+        for(auto& op_comb : op_combinations) {
+            uint64_t result = values[0];
+            for(uint64_t i = 1; i < values.size(); i++) {
+                result = defined_ops[op_comb[i-1]](result, values[i]);
+                if(result > test) break; 
+            }
+            if(result == test) {
+                acc += test;
+                break;
+            }
+        }
+    }
+    
+    return acc;
+} 
+
+int main() {
+    std::chrono::steady_clock::time_point begin = std::chrono::steady_clock::now();
+    auto p1_val = part_1();
+    std::chrono::steady_clock::time_point middle = std::chrono::steady_clock::now();
+    auto p2_val = part_2();
+    std::chrono::steady_clock::time_point end = std::chrono::steady_clock::now();
+    cout << "Part 1: " << p1_val << " (" << std::chrono::duration_cast<std::chrono::microseconds>(middle - begin).count() << "µs)" << endl;  
+    cout << "Part 2: " << p2_val << " (" << std::chrono::duration_cast<std::chrono::microseconds>(end - middle).count() << "µs)" << endl;
     return 0;
 }