Initial work on day 22.

2019/src/day22.cpp

@@ -1,7 +1,30 @@
 #include <iostream>
 #include "days.hpp"
+#include "utils.hpp"
 
 void aoc2019::day22_part1(std::istream &input, std::ostream &output) {
+    std::int64_t increment = 1;
+    std::int64_t offset = 0;
+
+    constexpr std::int64_t DECK_SIZE = 10007;
+
+    std::string buffer;
+    while (std::getline(input, buffer)) {
+        std::string_view line = buffer;
+        if (!line.find("deal into new stack")) {
+            increment *= -1;
+        } else if (!line.find("deal with increment ")) {
+            std::int64_t new_increment;
+            from_chars(line.substr(20), new_increment);
+            increment *= new_increment;
+            increment %= DECK_SIZE;
+        } else {
+            std::int64_t new_offset;
+            from_chars(line, new_offset);
+            offset += increment * new_offset;
+            offset %= DECK_SIZE;
+        }
+    }
 	output << "Not implemented\n";
 }