Day2Part1

day2/main.cpp

@@ -0,0 +1,83 @@
+#include <iostream>
+#include <fstream>
+#include <string>
+#include <vector>
+#include <expected>
+#include <print>
+#include <ranges>
+
+struct IDRange {
+    std::string leftRange;
+    std::string rightRange;
+};
+
+auto parseRanges(const std::string& filename) -> std::expected<std::vector<IDRange>, std::string> { 
+    std::ifstream inputF {filename};
+    
+    if (!inputF){
+        return std::unexpected{"Some file open error.\n"};
+    }
+    std::vector<IDRange> idRanges{}; 
+
+    std::string bigString{};
+    std::getline(inputF,bigString);
+    auto ranges = std::ranges::to<std::vector<std::string>>(std::views::split(bigString, ','));
+
+    for(const auto& range : ranges){
+        auto subParts = std::ranges::to<std::vector<std::string>>(std::views::split(range, '-'));
+        idRanges.emplace_back(subParts[0], subParts[1]);
+    }
+
+    inputF.close();
+
+    return std::move(idRanges);
+}
+
+
+
+auto countDoubles(const std::vector<IDRange>& idRanges) {
+    long doubles{};
+    for(const auto& rng : idRanges){
+        //std::println("{}-{}", rng.leftRange, rng.rightRange);
+        for( long i = std::stol(rng.leftRange); i <= std::stol(rng.rightRange); i++){
+            auto str_version = std::to_string(i) ;
+            auto str_len = str_version.size();
+            //std::print("Checking {}. Length: {}", str_version, str_version.size());
+            if (str_len % 2 == 0) {
+                //std::print(" Divisible by two, splitting...");
+                std::string_view left_half = std::string_view(str_version).substr(0, str_len/2);
+                std::string_view right_half = std::string_view(str_version).substr(str_len/2, str_len);
+                //std::print("Halves: {}/{}",left_half, right_half);
+                if(left_half == right_half){
+                    //std::print(" EQUAL!");
+                    doubles += i;
+                }
+            }
+            //std::println();
+        }
+    }
+    return doubles;
+}   
+
+auto main() -> int {
+    auto testCase = parseRanges("test_input");
+    if(testCase) {
+            auto testResult = countDoubles(*testCase);
+            std::println("Testcase result: {}", testResult);
+    }
+    else{
+        std::print("{}\n", testCase.error());    
+    }
+
+
+    auto realRanges = parseRanges("puzzle_input");
+    if(realRanges) {
+            auto realResult = countDoubles(*realRanges);
+            std::println("Real result: {}", realResult);
+    }
+    else{
+        std::print("{}\n", realRanges.error());    
+    }
+    
+    return 0;
+}