From a86449e97b0201af1aa71f5ba3a569975ff0c61c Mon Sep 17 00:00:00 2001
From: Orfeas <38209077+0xfea5@users.noreply.github.com>
Date: Thu, 4 Dec 2025 03:59:35 +0200
Subject: day02

---
 day02/solution.cpp | 85 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 85 insertions(+)
 create mode 100644 day02/solution.cpp

(limited to 'day02/solution.cpp')

diff --git a/day02/solution.cpp b/day02/solution.cpp
new file mode 100644
index 0000000..23304c1
--- /dev/null
+++ b/day02/solution.cpp
@@ -0,0 +1,85 @@
+#include <bits/stdc++.h>
+
+namespace views = std::views;
+namespace ranges = std::ranges;
+
+auto parse_input(std::istream& is) {
+    const std::string input = {
+        std::istreambuf_iterator<char>(is),
+        std::istreambuf_iterator<char>()
+    };
+
+    auto char_range_to_int = [](auto&& r) {
+        auto&& s = ranges::to<std::string>(r);
+        return std::stoll(s);
+    };
+    auto lines = views::split(input, ',')
+            | views::filter([](auto line) { return not line.empty(); });
+
+    std::vector<std::pair<long, long>> _ranges;
+    for (auto const line : lines) {
+        auto numbers = line
+            | views::split('-')
+            | views::transform(char_range_to_int);
+        _ranges.emplace_back(*numbers.begin(), *std::next(numbers.begin()));
+    }
+    return _ranges;
+}
+
+
+void part1(auto const& input) {
+    // Write first part solution here
+    long answer = 0;
+
+    for (auto [begin, end] : input) {
+        for (auto i = begin; i <= end; ++i) {
+            std::string s{std::format("{}", i)};
+            size_t half_size = s.size() / 2;
+            std::string_view sl{s.begin(), s.begin() + half_size};
+            std::string_view sr{s.begin() + half_size, s.end()};
+            if (sl == sr) {
+                answer += i;
+            }
+        }
+    }
+
+    std::println("{}", answer);
+}
+
+void part2(auto const& input) {
+    // Write second part solution here
+    long answer = 0;
+
+    for (auto [begin, end] : input) {
+        for (auto i = begin; i <= end; ++i) {
+            std::stringstream ss;
+            ss << i;
+            std::string_view s{ss.str()};
+            for (int chunk_size = 1; chunk_size <= s.size() / 2; ++chunk_size) {
+                if (s.size() % chunk_size != 0) {
+                    continue;
+                }
+                auto chunks = s | views::chunk(chunk_size);
+                auto value = *chunks.begin();
+                if (ranges::all_of(chunks, [value](auto&& chunk) {
+                    return ranges::equal(chunk, value);
+                })) {
+                    answer += i;
+                    break;
+                }
+            }
+        }
+    }
+
+    std::println("{}", answer);
+
+}
+
+int main() {
+    auto const input = parse_input(std::cin);
+
+    part1(input);
+    part2(input);
+
+    return 0;
+}
-- 
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