From 38db41f6aedc73baafa721031373588e4f1445ac Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Andr=C3=A9=20Apitzsch?= <andre.apitzsch@etit.tu-chemnitz.de>
Date: Fri, 2 Aug 2024 09:57:03 +0200
Subject: [PATCH] CoinBronKerbosch: Replace magic number for pivoting strategy

---
 src/CoinBronKerbosch.cpp | 16 ++++++++--------
 src/CoinBronKerbosch.hpp | 32 +++++++++++++++++++-------------
 2 files changed, 27 insertions(+), 21 deletions(-)

diff --git a/src/CoinBronKerbosch.cpp b/src/CoinBronKerbosch.cpp
index 886b77b9..a8b19655 100644
--- a/src/CoinBronKerbosch.cpp
+++ b/src/CoinBronKerbosch.cpp
@@ -40,7 +40,7 @@ bool compareNodes(const BKVertex &u, const BKVertex &v) {
     return u.fitness >= v.fitness + BK_EPS;
 }
 
-CoinBronKerbosch::CoinBronKerbosch(const CoinConflictGraph *cgraph, const double *weights, size_t pivotingStrategy)
+CoinBronKerbosch::CoinBronKerbosch(const CoinConflictGraph *cgraph, const double *weights, PivotingStrategy pivotingStrategy)
   : nVertices_(0)
   , minWeight_(0.0)
   , calls_(0)
@@ -351,14 +351,14 @@ size_t CoinBronKerbosch::numCalls() const {
 
 void CoinBronKerbosch::computeFitness(const double *weights) {
     switch (pivotingStrategy_) {
-        case 0:
+        case PivotingStrategy::Off:
             //do nothing
             break;
-        case 1: { //random
+        case PivotingStrategy::Random: {
             shuffle_vertices(vertices_, nVertices_);
             break;
         }
-        case 2: { //degree
+        case PivotingStrategy::Degree: {
             for (size_t u = 0; u < nVertices_; u++) {
                 const size_t uIdx = vertices_[u].idx;
                 vertices_[u].fitness = cgraph_->degree(uIdx);
@@ -366,7 +366,7 @@ void CoinBronKerbosch::computeFitness(const double *weights) {
             std::sort(vertices_, vertices_ + nVertices_, compareNodes);
             break;
         }
-        case 3: { //weight
+        case PivotingStrategy::Weight: {
             for (size_t u = 0; u < nVertices_; u++) {
                 const size_t uIdx = vertices_[u].idx;
                 vertices_[u].fitness = weights[uIdx];
@@ -374,7 +374,7 @@ void CoinBronKerbosch::computeFitness(const double *weights) {
             std::sort(vertices_, vertices_ + nVertices_, compareNodes);
             break;
         }
-        case 4: { //modified degree
+        case PivotingStrategy::ModifiedDegree: {
             for (size_t u = 0; u < nVertices_; u++) {
                 const size_t uIdx = vertices_[u].idx;
                 vertices_[u].fitness = cgraph_->modifiedDegree(uIdx);
@@ -382,7 +382,7 @@ void CoinBronKerbosch::computeFitness(const double *weights) {
             std::sort(vertices_, vertices_ + nVertices_, compareNodes);
             break;
         }
-        case 5: { //modified weight
+        case PivotingStrategy::ModifiedWeight: {
             size_t *neighs = (size_t*)xmalloc(sizeof(size_t) * cgraph_->size());
             char *iv = (char*)xcalloc(cgraph_->size(), sizeof(char));
             for (size_t u = 0; u < nVertices_; u++) {
@@ -399,7 +399,7 @@ void CoinBronKerbosch::computeFitness(const double *weights) {
             std::sort(vertices_, vertices_ + nVertices_, compareNodes);
             break;
         }
-        case 6: { //modified degree + modified weight
+        case PivotingStrategy::ModifiedDegreeWeight: {
             size_t *neighs = (size_t*)xmalloc(sizeof(size_t) * cgraph_->size());
             char *iv = (char*)xcalloc(cgraph_->size(), sizeof(char));
             for (size_t u = 0; u < nVertices_; u++) {
diff --git a/src/CoinBronKerbosch.hpp b/src/CoinBronKerbosch.hpp
index 39350810..ace75fbd 100644
--- a/src/CoinBronKerbosch.hpp
+++ b/src/CoinBronKerbosch.hpp
@@ -59,16 +59,28 @@ struct BKVertex {
  **/
 class COINUTILSLIB_EXPORT CoinBronKerbosch {
 public:
+  /**
+   * Pivoting strategies used in BK algorithm.
+   **/
+  enum PivotingStrategy {
+    Off = 0,
+    Random = 1,
+    Degree = 2,
+    Weight = 3,
+    ModifiedDegree = 4,
+    ModifiedWeight = 5,
+    ModifiedDegreeWeight = 6,
+  };
+
   /**
    * Default constructor.
    *
    * @param cgraph conflict graph
    * @param weights array containing the weights for each vertex
-   * @param pivotingStrategy pivoting strategy used in BK algorithm. Values:
-   * 0 = off; 1 = random; 2 = degree; 3 = weight; 4 = modified degree;
-   * 5 = modified weight; 6 = modified degree + modified weight. Default: 3
+   * @param pivotingStrategy pivoting strategy used in BK algorithm.
    **/
-  CoinBronKerbosch(const CoinConflictGraph *cgraph, const double *weights, size_t pivotingStrategy = 3);
+  CoinBronKerbosch(const CoinConflictGraph *cgraph, const double *weights,
+    PivotingStrategy pivotingStrategy = PivotingStrategy::Weight);
 
   /**
    * Destructor
@@ -232,16 +244,10 @@ class COINUTILSLIB_EXPORT CoinBronKerbosch {
      **/
     size_t maxCalls_;
 
-    /** Pivoting strategy used in BK algorithm. Options:
-     * 0 - off
-     * 1 - random
-     * 2 - degree
-     * 3 - weight
-     * 4 - modified degree
-     * 5 - modified weight
-     * 6 - modified degree + modified weight
+    /**
+     * Pivoting strategy used in BK algorithm.
      **/
-    size_t pivotingStrategy_;
+    PivotingStrategy pivotingStrategy_;
 
     /**
      * If BK algorithm ran completely, without stopping