depth first search

Former-commit-id: fd13e2762f92d8f9b97db8b1b9d68106322ec4f3

include/igl/dfs.cpp

@@ -0,0 +1,54 @@
+#include "dfs.h"
+#include "list_to_matrix.h"
+#include <vector>
+
+template <
+  typename AType,
+  typename DerivedD,
+  typename DerivedP,
+  typename DerivedC>
+IGL_INLINE void igl::dfs(
+  const std::vector<std::vector<AType> > & A,
+  const size_t s,
+  Eigen::PlainObjectBase<DerivedD> & D,
+  Eigen::PlainObjectBase<DerivedP> & P,
+  Eigen::PlainObjectBase<DerivedC> & C)
+{
+  std::vector<typename DerivedD::Scalar> vD;
+  std::vector<typename DerivedP::Scalar> vP;
+  std::vector<typename DerivedC::Scalar> vC;
+  dfs(A,s,vD,vP,vC);
+  list_to_matrix(vD,D);
+  list_to_matrix(vP,P);
+  list_to_matrix(vC,C);
+}
+
+template <
+  typename AType,
+  typename DType,
+  typename PType,
+  typename CType>
+IGL_INLINE void igl::dfs(
+  const std::vector<std::vector<AType> > & A,
+  const size_t s,
+  std::vector<DType> & D,
+  std::vector<PType> & P,
+  std::vector<CType> & C)
+{
+  // number of nodes
+  int N = 0;
+  for(const auto & Ai : A) for(const auto & a : Ai) N = std::max(N,a+1);
+  std::vector<bool> seen(N,false);
+  P.resize(N,-1);
+  std::function<void(const size_t, const size_t)> dfs_helper;
+  dfs_helper = [&D,&P,&C,&dfs_helper,&seen,&A](const size_t s, const size_t p)
+  {
+    if(seen[s]) return;
+    seen[s] = true;
+    D.push_back(s);
+    P[s] = p;
+    for(const auto n : A[s]) dfs_helper(n,s);
+    C.push_back(s);
+  };
+  dfs_helper(s,-1);
+}