欧拉回路的建立方式

Program EulerPath_Algorithm;
(**************************************************************************}
{ An Euler path (pronounced 'oiler') in a graph G is a path that uses each }
{ arc of G exactly once and can exist in a connected graph iff there are }
{ either no nodes whose degree is odd or exactly two nodes whose degree is }
{ odd. For the case of no nodes posessing an odd degree, the path can }
{ begin at any node and will end there; for the case of two nodes posessing}
{ an odd degree, the path must begin at one odd node and end at the other. }
{--------------------------------------------------------------------------}
{ Released to the public domain by Natural Systems. This routine may be }
{ freely distributed. }
{--------------------------------------------------------------------------}
{ Natural Systems is the producer of DATA STRUCTURES