From d0243fcf4d5556a17d720257ecc0097ecfd69df8 Mon Sep 17 00:00:00 2001
From: Bert Peters <bert@bertptrs.nl>
Date: Tue, 17 Dec 2019 07:28:39 +0100
Subject: [PATCH] Create generic bounding box function.

---
 2019/src/day11.cpp | 13 +++----------
 2019/src/day13.cpp | 12 +++---------
 2019/src/point.hpp | 16 ++++++++++++++++
 3 files changed, 22 insertions(+), 19 deletions(-)

diff --git a/2019/src/day11.cpp b/2019/src/day11.cpp
index 2dd8302..21fb882 100644
--- a/2019/src/day11.cpp
+++ b/2019/src/day11.cpp
@@ -64,17 +64,10 @@ void aoc2019::day11_part2(std::istream &input, std::ostream &output) {
     const auto result = simulate(input, true);
 
     // Determine bounding box
-    using limits = std::numeric_limits<int>;
-    int left_edge = limits::max(), right_edge = limits::min(), top_edge = limits::max(), bottom_edge = limits::min();
-    for (auto& entry : result) {
-        left_edge = std::min(entry.first[0], left_edge);
-        right_edge = std::max(entry.first[0], right_edge);
-        top_edge = std::min(entry.first[1], top_edge);
-        bottom_edge = std::max(entry.first[1], bottom_edge);
-    }
+    auto[lower,upper] = aoc2019::bounding_box(result);
 
-    for (int y = top_edge; y <= bottom_edge; ++y) {
-        for (int x = left_edge; x <= right_edge; ++x) {
+    for (int y = lower[1]; y <= upper[1]; ++y) {
+        for (int x = lower[0]; x <= upper[0]; ++x) {
             if (auto it = result.find({x, y}); it != result.end() && it->second) {
                 output << '#';
             } else {
diff --git a/2019/src/day13.cpp b/2019/src/day13.cpp
index aba4aeb..f8625e6 100644
--- a/2019/src/day13.cpp
+++ b/2019/src/day13.cpp
@@ -41,16 +41,10 @@ namespace {
         // Determine bounding box
         using limits = std::numeric_limits<int>;
 
-        std::int64_t left_edge = limits::max(), right_edge = limits::min(), top_edge = limits::max(), bottom_edge = limits::min();
-        for (auto& entry : screen) {
-            left_edge = std::min(entry.first[0], left_edge);
-            right_edge = std::max(entry.first[0], right_edge);
-            top_edge = std::min(entry.first[1], top_edge);
-            bottom_edge = std::max(entry.first[1], bottom_edge);
-        }
+        const auto [lower, upper] = aoc2019::bounding_box(screen);
 
-        for (auto y = top_edge; y <= bottom_edge; ++y) {
-            for (auto x = left_edge; x <= right_edge; ++x) {
+        for (auto y = lower[1]; y <= upper[1]; ++y) {
+            for (auto x = lower[0]; x <= upper[0]; ++x) {
                 char c = ' ';
                 if (auto it = screen.find({x, y}); it != screen.end()) {
                     switch (it->second) {
diff --git a/2019/src/point.hpp b/2019/src/point.hpp
index f82bbad..d123475 100644
--- a/2019/src/point.hpp
+++ b/2019/src/point.hpp
@@ -46,6 +46,22 @@ namespace aoc2019 {
             return result;
         }
     };
+
+    template<typename ValueType, std::size_t N, typename Ignored>
+    std::pair<Point<ValueType, N>, Point<ValueType, N>> bounding_box(const std::unordered_map<Point<ValueType, N>, Ignored> &data) {
+        Point<ValueType, N> lower, upper;
+        std::fill(lower.begin(), lower.end(), std::numeric_limits<ValueType>::max());
+        std::fill(upper.begin(), upper.end(), std::numeric_limits<ValueType>::min());
+
+        for (auto &entry : data) {
+            for (int i = 0; i < N; ++i) {
+                lower[i] = std::min(entry.first[i], lower[i]);
+                upper[i] = std::max(entry.first[i], upper[i]);
+            }
+        }
+
+        return {lower, upper};
+    }
 }
 
 namespace std {