Moved coordinate calculation to construction

1 files changed, 7 insertions, 3 deletions

diff --git a/percolation.cpp b/percolation.cpp
index a5c2a36..f012b07 100644
--- a/percolation.cpp
+++ b/percolation.cpp
@@ -26,6 +26,7 @@ class Vertex {
 public:
   std::vector<HalfEdge> bonds;
   unsigned index;
+  std::vector<unsigned> coordinates;
 };
 
 class Cluster : public std::list<std::reference_wrapper<const Vertex>> {};
@@ -60,8 +61,8 @@ public:
   unsigned squaredDistance(unsigned vi, unsigned vj) const {
     unsigned sd = 0;
     for (unsigned i = 0; i < D; i++) {
-      int x1 = (vi / uPow(L, i)) % uPow(L, i + 1);
-      int x2 = (vj / uPow(L, i)) % uPow(L, i + 1);
+      int x1 = vertices[vi].coordinates[i];
+      int x2 = vertices[vj].coordinates[i];
       unsigned Δx = abs(x1 - x2);
       if (Δx > L / 2) {
         Δx = L - Δx;
@@ -72,11 +73,14 @@ public:
   }
 
   /* Initialize a square lattice */
-  Graph(unsigned D, unsigned L) : D(D), L(L), vertices(uPow(L, D)), multiplicities(D * L * L / 4) {
+  Graph(unsigned D, unsigned L) : D(D), L(L), vertices(uPow(L, D)), multiplicities((D * L * L) / 4) {
     for (unsigned i = 0; i < Nv(); i++) {
+      vertices[i].coordinates.resize(D);
       vertices[i].index = i;
       vertices[i].bonds.reserve(2 * D);
       for (unsigned j = 0; j < D; j++) {
+        vertices[i].coordinates[j] = (i / uPow(L, j)) % L;
+
         unsigned n1 = uPow(L, j + 1) * (i / uPow(L, j + 1)) + (i + uPow(L, j)) % uPow(L, j + 1);
         unsigned n2 = uPow(L, j + 1) * (i / uPow(L, j + 1)) + (uPow(L, j + 1) + i - uPow(L, j)) % uPow(L, j + 1);