3

Author: gogsbread

cpp/3.cpp

@@ -0,0 +1,38 @@
+#include "common.h"
+
+namespace {
+long p1(const auto &input) {
+  long p{0};
+  for (auto l : input) {
+    long m = static_cast<long>(l.length() / 2);
+    auto c1 = l | std::ranges::views::take(m);
+    std::ranges::sort(c1);
+    auto c2 = l | std::ranges::views::drop(m);
+    std::ranges::sort(c2);
+    std::string s;
+    std::ranges::set_intersection(c1, c2, std::back_inserter(s));
+    p += (std::isupper(s[0])) ? (s[0] - '@') + 26 : (s[0] - '`');
+  }
+  return p;
+}
+
+long p2(auto input) {
+  long p{};
+  constexpr size_t sz = 3;
+  for (size_t d{}; d < input.size(); d += sz) {
+    auto g = input | std::ranges::views::drop(d) | std::ranges::views::take(sz);
+    std::ranges::for_each(g, [](auto &gi) { std::ranges::sort(gi); });
+    std::string int1{}, int2{};
+    std::ranges::set_intersection(g[0], g[1], std::back_inserter(int1));
+    std::ranges::set_intersection(g[2], int1, std::back_inserter(int2));
+    p += (std::isupper(int2[0])) ? (int2[0] - '@') + 26 : (int2[0] - '`');
+  }
+  return p;
+}
+} // namespace
+
+int main() {
+  const auto &input = gb::advent2021::readIn();
+  gb::advent2021::writeOut(std::to_string(p1(input)));
+  gb::advent2021::writeOut(std::to_string(p2(input)));
+}

cpp/common.h

@@ -1,5 +1,6 @@
 #include <algorithm>
 #include <bitset>
+#include <cctype>
 #include <climits>
 #include <cmath>
 #include <cstdint>
@@ -11,6 +12,7 @@
 #include <map>
 #include <memory>
 #include <numeric>
+#include <ranges>
 #include <set>
 #include <sstream>
 #include <stack>

cpp/meson.build

@@ -1,6 +1,6 @@
 project('advent2022', 'cpp',
   version : '0.1',
-  default_options : ['warning_level=3', 'cpp_std=c++2a'])
+  default_options : ['warning_level=3', 'cpp_std=c++20'])
 
 executable('1',
     '1.cpp',
@@ -10,9 +10,9 @@ executable('2',
     '2.cpp',
     dependencies: [])
 
-# executable('3',
-#     '3.cpp',
-#     dependencies: [])
+executable('3',
+    '3.cpp',
+    dependencies: [])
 
 # executable('4',
 #     '4.cpp',