From dc0eba6de4807dfc335c5ba31cdeff71e5eed717 Mon Sep 17 00:00:00 2001
From: Orfeas <38209077+0xfea5@users.noreply.github.com>
Date: Sat, 27 Dec 2025 12:55:32 +0200
Subject: day05

---
 day05/solution.cpp | 84 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 84 insertions(+)
 create mode 100644 day05/solution.cpp

(limited to 'day05/solution.cpp')

diff --git a/day05/solution.cpp b/day05/solution.cpp
new file mode 100644
index 0000000..fa4ff87
--- /dev/null
+++ b/day05/solution.cpp
@@ -0,0 +1,84 @@
+#include <bits/stdc++.h>
+
+namespace views = std::views;
+namespace ranges = std::ranges;
+using set = std::pair<uint64_t, uint64_t>;
+
+auto parse_input(std::istream& is) {
+    const std::string input = {
+        std::istreambuf_iterator<char>(is),
+        std::istreambuf_iterator<char>()
+    };
+
+    auto const lines = input
+        | views::split(std::string_view{"\n\n"})
+        | views::filter([](auto&& line) { return not line.empty(); })
+        | ranges::to<std::vector<std::string>>();
+
+    auto const sets = lines[0]
+        | views::split('\n')
+        | views::filter([](auto&& line) { return not line.empty(); })
+        | views::transform([](auto&& element) -> set {
+            auto const l = element | views::split('-') | ranges::to<std::vector<std::string>>();
+            return set{std::stoull(l[0]), std::stoull(l[1])};
+        })
+        | ranges::to<std::vector<set>>();
+
+    auto const numbers = lines[1]
+        | views::split('\n')
+        | views::filter([](auto&& line) { return not line.empty(); })
+        | views::transform([](auto&& elem) -> uint64_t { return std::stoull(elem | ranges::to<std::string>()); })
+        | ranges::to<std::vector>();
+
+    // Parse input
+    return std::make_tuple(sets, numbers);
+}
+
+void part1(auto const& input) {
+    // Write first part solution here
+    auto const& [sets, numbers] = input;
+    uint64_t answer = 0;
+    for (auto const n : numbers) {
+        answer += ranges::count_if(sets, [n](auto const& set) { return set.first <= n and n <= set.second; }) > 0;
+    }
+    std::println("{}", answer);
+}
+
+std::vector<set> merge_sets(std::vector<set> sets) {
+    ranges::sort(sets);
+
+    std::vector merged_sets = {sets[0]};
+    merged_sets.reserve(sets.size());
+
+    for (auto const& next : sets) {
+        auto& last = merged_sets.back();
+        if (last.second + 1 < next.first) {
+            // gap: [(1, 5), (7, 12)]
+            merged_sets.push_back(next);
+        } else {
+            // no gap: [(1, 5), (4, 8)]
+            last.second = std::max(last.second, next.second);
+        }
+    }
+
+    return merged_sets;
+}
+
+void part2(auto const& input) {
+    // Write second part solution here
+    auto const& [sets, numbers] = input;
+    auto const merged_sets = merge_sets(sets);
+    uint64_t answer = 0;
+    for (auto const set : merged_sets) {
+        answer += set.second - set.first + 1;
+    }
+    std::println("{}", answer);
+}
+
+int main() {
+    auto const input = parse_input(std::cin);
+    part1(input);
+    part2(input);
+
+    return 0;
+}
-- 
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