diff --git a/cpp/graph.hpp b/cpp/graph.hpp
index 6585dbd12d79407616158c9bd3d7108ed08eef51..13f997a413f3e565161162a31b8808f43b32d99d 100644
--- a/cpp/graph.hpp
+++ b/cpp/graph.hpp
@@ -145,7 +145,8 @@ class Graph {
     // There are two possible edge exchanges
     // switchType indicates which one is desired
     // Returns false if the switch is not possible
-    bool exchangeEdges(unsigned int e1index, unsigned int e2index, bool switchType) {
+    bool exchangeEdges(unsigned int e1index, unsigned int e2index,
+                       bool switchType, bool trackTriangles = false) {
         StoredEdge &se1 = edges[e1index];
         StoredEdge &se2 = edges[e2index];
         const Edge &e1 = se1.e;
@@ -165,6 +166,11 @@ class Graph {
         if (hasEdge({e1.u, e2.u}) || hasEdge({e1.v, e2.v}))
             return false; // conflicting edges
 
+        if (trackTriangles) {
+            trackedTriangles -= countTriangles(e1);
+            trackedTriangles -= countTriangles(e2);
+        }
+
         // Clear old edges
         badj[e1.u][e1.v] = false;
         badj[e1.v][e1.u] = false;
@@ -183,11 +189,30 @@ class Graph {
         badj[e1.v][e1.u] = true;
         badj[e2.u][e2.v] = true;
         badj[e2.v][e2.u] = true;
+
+        if (trackTriangles) {
+            trackedTriangles += countTriangles(e1);
+            trackedTriangles += countTriangles(e2);
+        }
+
         return true;
     }
 
-    int countTriangles() const {
-        int triangles = 0;
+    // Assumes edge exists
+    // Used for computing triangle-delta's after switch move
+    unsigned int countTriangles(Edge e) const {
+        auto triangles = 0u;
+        if (adj[e.u].size() > adj[e.v].size())
+            std::swap(e.u, e.v);
+        for (auto w : adj[e.u]) {
+            if (hasEdge({w, e.v}))
+                ++triangles;
+        }
+        return triangles;
+    }
+
+    unsigned int countTriangles() const {
+        auto triangles = 0u;
         for (auto& v : adj) {
             for (unsigned int i = 0; i < v.size(); ++i) {
                 for (unsigned int j = i + 1; j < v.size(); ++j) {
@@ -201,6 +226,8 @@ class Graph {
         return triangles / 3;
     }
 
+    unsigned int& getTrackedTriangles() { return trackedTriangles; }
+
     // Should return zero
     int consistencyCheck() const {
         // Check if info in 'edges' is present
@@ -254,5 +281,6 @@ class Graph {
     std::vector<std::vector<unsigned int>> adj;
     std::vector<std::vector<bool>> badj; // symmetric binary matrix
     std::vector<StoredEdge> edges;
+    unsigned int trackedTriangles;
 };