Use **Combinations** rather than **Permutations** when matching surfa…

…ces/edges

Testbed / demo: https://godbolt.org/z/E7n88WP34

src/utilities/geometry/Polyhedron.cpp

@@ -111,6 +111,8 @@ std::ostream& operator<<(std::ostream& os, const Surface3dEdge& edge) {
 
 Surface3d::Surface3d(std::vector<Point3d> t_vertices, std::string t_name, size_t t_surfNum)
   : vertices(std::move(t_vertices)), name(std::move(t_name)), surfNum(t_surfNum) {
+
+  edges.reserve(vertices.size());
   for (auto it = vertices.begin(); it != vertices.end(); ++it) {
 
     auto itnext = std::next(it);
@@ -240,11 +242,9 @@ void Polyhedron::performEdgeMatching() {
 
   m_hasAnySurfaceWithIncorrectOrientation = false;
 
-  for (size_t i = 0; i < m_surfaces.size(); ++i) {
-    for (size_t j = 0; j < m_surfaces.size(); ++j) {
-      if (i == j) {
-        continue;
-      }
+  // We use **Combinations** (rather than Permutations) to avoid traversing unnecessarily
+  for (size_t i = 0; i < m_surfaces.size() - 1; ++i) {
+    for (size_t j = i + 1; j < m_surfaces.size(); ++j) {
       auto& surface1 = m_surfaces[i];
       auto& surface2 = m_surfaces[j];
       for (Surface3dEdge& edge1 : surface1.edges) {
@@ -273,11 +273,8 @@ void Polyhedron::performEdgeMatching() {
   // we allow these edges to double count the first surface since they bound the same surface on two sides
   for (auto& surface : m_surfaces) {
     auto& edges = surface.edges;
-    for (size_t i = 0; i < edges.size(); ++i) {
-      for (size_t j = 0; j < edges.size(); ++j) {
-        if (i == j) {
-          continue;
-        }
+    for (size_t i = 0; i < edges.size() - 1; ++i) {
+      for (size_t j = i + 1; j < edges.size(); ++j) {
         if ((edges[i].count() == 1) && (edges[j].count() == 1) && (edges[i] == edges[j]) && edges[i].reverseEqual(edges[j])) {
           // appendSurface will allow use to check edge.count() later to check if count == 2.
           // All edges must be count == 2 in an Enclosed Polyhedron