2023 Day 1

2023/puzzle-01-01.cc

@@ -0,0 +1,65 @@
+#include <cassert>
+#include <cstdlib>
+#include <iostream>
+#include <string>
+
+using UInt = std::uint64_t;
+
+constexpr std::array nums = {
+  std::make_pair("one", 1), std::make_pair("two", 2), std::make_pair("three", 3),
+  std::make_pair("four", 4),
+  std::make_pair("five", 5), std::make_pair("six", 6),
+  std::make_pair("seven", 7),
+  std::make_pair("eight", 8), std::make_pair("nine", 9)};
+
+auto find_first_digit(std::string const& line) -> int
+{
+  auto pos = line.find_first_of("0123456789");
+  auto value = line[pos] - '0';
+  for (auto [s, v] : nums) {
+    if (auto p = line.find(s); p != std::string::npos) {
+      if (p < pos) {
+        pos = p;
+        value = v;
+      }
+    }
+  }
+  return value;
+}
+
+auto find_last_digit(std::string const& line) -> int
+{
+  auto pos = line.find_last_of("0123456789");
+  auto value = line[pos] - '0';
+  for (auto [s, v] : nums) {
+    if (auto p = line.rfind(s); p != std::string::npos) {
+      if (p > pos) {
+        pos = p;
+        value = v;
+      }
+    }
+  }
+  return value;
+}
+
+auto main() -> int
+{
+  UInt sum1{0};
+  UInt sum2{0};
+
+  std::string line;
+  while (std::getline(std::cin, line)) {
+    auto first = line.find_first_of("0123456789");
+    auto last = line.find_last_of("0123456789");
+    assert(first != std::string::npos);
+    assert(last != std::string::npos);
+    sum1 += (line[first] - '0') * 10;
+    sum1 += (line[last] - '0');
+    sum2 += find_first_digit(line) * 10;
+    sum2 += find_last_digit(line);
+  }
+
+  std::cout << "Sum 1: " << sum1 << "\n";
+  std::cout << "Sum 2: " << sum2 << "\n";
+  return EXIT_SUCCESS;
+}