1 files changed, 95 insertions, 0 deletions

diff --git a/2018/src/day03.cpp b/2018/src/day03.cpp
new file mode 100644
index 0000000..bed3acb
--- /dev/null
+++ b/2018/src/day03.cpp
@@ -0,0 +1,95 @@
+#include <filesystem>
+#include <fstream>
+#include <iostream>
+#include <map>
+#include <regex>
+#include <set>
+#include <tuple>
+#include <vector>
+
+using namespace std;
+
+namespace {
+
+struct Claim {
+        int id;
+        int left;
+        int top;
+        int width;
+        int height;
+};
+
+#if 0
+ostream&
+operator<<(ostream& ostrm, const Claim& claim)
+{
+        ostrm << "id: " << claim.id
+              << " (" << claim.left << ", " << claim.top << ": " << claim.width << "x" << claim.height;
+        return ostrm;
+}
+#endif
+
+vector<Claim>
+read_file(const filesystem::path& filename)
+{
+        ifstream      file{ filename };
+        vector<Claim> claims;
+
+        regex  pattern(R"#((\d+) @ (\d+),(\d+): (\d+)x(\d+))#");
+        smatch match;
+
+        for ( string line; getline(file, line); ) {
+                if ( !regex_search(line, match, pattern) ) {
+                        continue;
+                }
+
+                Claim claim{};
+                claim.id     = stoi(match[1]);
+                claim.left   = stoi(match[2]);
+                claim.top    = stoi(match[3]);
+                claim.width  = stoi(match[4]);
+                claim.height = stoi(match[5]);
+
+                claims.emplace_back(claim);
+        }
+
+        return claims;
+}
+
+void
+solve(const vector<Claim>& claims)
+{
+        map<tuple<int, int>, vector<int>> fabric;
+        set<int>                          allIds;
+
+        for ( const auto& claim: claims ) {
+                for ( int x = claim.left; x < claim.left + claim.width; ++x ) {
+                        for ( int y = claim.top; y < claim.top + claim.height; ++y ) {
+                                fabric[{ x, y }].emplace_back(claim.id);
+                        }
+                }
+                allIds.emplace(claim.id);
+        }
+
+        int overlapCount = 0;
+        for ( const auto& [pos, ids]: fabric ) {
+                if ( ids.size() > 1 ) {
+                        ++overlapCount;
+                        for ( const auto& id: ids ) {
+                                allIds.erase(id);
+                        }
+                }
+        }
+
+        cout << "Part 1: " << overlapCount << '\n';
+        cout << "Part 2: " << *allIds.begin() << '\n';
+}
+
+} // namespace
+
+int
+main()
+{
+        auto claims = read_file("data/day03.txt");
+        solve(claims);
+}