1 files changed, 84 insertions, 0 deletions

diff --git a/2023/05/src/part1.cpp b/2023/05/src/part1.cpp
new file mode 100644
index 0000000..d58c0cb
--- /dev/null
+++ b/2023/05/src/part1.cpp
@@ -0,0 +1,84 @@
+#include <iostream>
+#include <fstream>
+#include <sstream>
+#include <tuple>
+#include <vector>
+
+#include "util.h"
+
+using Seeds   = std::vector<long>;
+using Step    = std::vector<std::tuple<long,long,long>>;
+using Almanac = std::vector<Step>;
+
+constexpr char SEEDS[] = "seeds:";
+
+std::pair<Seeds,Almanac> parse_input()
+{
+    Seeds seeds;
+    Almanac almanac;
+
+    std::ifstream input{ "resources/input.txt" };
+    if (input.is_open())
+    {
+        std::string line;
+
+        /* Seeds */
+        long seed;
+        std::getline(input,line);
+        std::istringstream sline{ line };
+        sline >> util::skip<SEEDS>;
+        while (sline >> seed)
+        {
+            seeds.push_back(seed);
+        }
+
+        /* Mappings */
+        Step step;
+        long from, to, size;
+        while (not std::getline(input,line).eof())
+        {
+            if (line.empty()) continue;
+
+            if (std::isdigit(line[0]))
+            {
+                std::istringstream sline{ line };
+                sline >> to >> from >> size;
+                step.push_back(std::make_tuple(from, from + size, to - from));
+            }
+            else if (not step.empty())
+            {
+                almanac.push_back(std::move(step));
+                step = {};
+            }
+        }
+        almanac.push_back(std::move(step));
+    }
+    input.close();
+
+    return std::make_pair(std::move(seeds), std::move(almanac));
+}
+
+int main(void)
+{
+    Seeds seeds;
+    Almanac almanac;
+    std::tie(seeds, almanac) = parse_input();
+
+    for (const auto& step : almanac)
+    {
+        for (auto& seed : seeds)
+        {
+            for (const auto& map : step)
+            {
+                if (std::get<0>(map) <= seed and seed < std::get<1>(map))
+                {
+                    seed += std::get<2>(map);
+                    break; // mappings in a step don't overlap
+                }
+            }
+        }
+    }
+
+    std::cout << *std::min_element(seeds.begin(), seeds.end()) << std::endl;
+    return 0;
+}