From 5077d7e966ddf077867b9badaf2ab9e6e01f90eb Mon Sep 17 00:00:00 2001
From: Joshua Moerman <lakseru@gmail.com>
Date: Mon, 17 Feb 2014 16:51:45 +0100
Subject: [PATCH] Small improvement in speed

---
 include/clusters.hpp | 28 +++++++++++++++++-----------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/include/clusters.hpp b/include/clusters.hpp
index bb7326e..4e98e42 100644
--- a/include/clusters.hpp
+++ b/include/clusters.hpp
@@ -2,6 +2,7 @@
 
 #include <boost/container/flat_set.hpp>
 #include <cassert>
+#include <utility>
 
 // Using boost flat set was faster than std::set.
 
@@ -41,18 +42,23 @@ auto cluster_at(Field const & field, typename Field::Position const & p){
 	return ret;
 }
 
-
-template <typename Field, typename Rules>
-auto all_clusters(Field const & field, Rules const & rules){
-	boost::container::flat_set<decltype(cluster_at(field, std::declval<typename Field::Position>()))> ret;
+template <typename Grid, typename Rules>
+auto all_clusters(Grid const & grid, Rules const & rules){
+	std::vector<decltype(cluster_at(grid, std::declval<typename Grid::Position>()))> ret;
 	ret.reserve(10);
-	for(auto&& p : field.all_positions()){
-		if(field.empty(p)) continue;
-		ret.insert(cluster_at(field, p));
-	}
-	for(auto it = ret.begin(); it != ret.end();){
-		if (it->size() < rules.min_cluster_size()) it = ret.erase(it);
-		else ++it;
+	auto partition = make_empty(grid, grid.all_positions());
+	auto current_p = 1;
+	for(auto&& p : partition.all_positions()){
+		if(!partition.empty(p) || grid.empty(p)) continue;
+
+		auto cluster = cluster_at(grid, p);
+		for(auto&& q : cluster){
+			partition.get(q) = current_p;
+		}
+
+		current_p++;
+		if(cluster.size() >= rules.min_cluster_size()) ret.push_back(std::move(cluster));
 	}
+
 	return ret;
 }