我的图类基本上由值和map
之间的Vertices
组成,其中每个Vertex
都是其自身的类。每个顶点都有一个值和一个邻接表,将其实现为相邻map
和边缘权重之间的Vertices
。我正在尝试显示图形中的每个顶点以及与之相邻的顶点,以及将其连接到其相邻顶点的边缘的权重。 (对不起所有代码)
template <class VertexType>
void Graph<VertexType>::display() const
{
typedef map<VertexType, Vertex<VertexType> >::iterator vertices_iter;
typedef map<Vertex<VertexType>, int>::iterator adjList_iter;
for ( vertices_iter v_iter = vertices.begin(); v_iter != vertices.end(); v_iter++ )
{
cout << "Vertex: " << v_iter->second.value << endl;
cout << setw(25) << left << "Adjacent to: " << "Edge weight:\n";
for ( adjList_iter a_iter = vertices[v_iter->first].adjList.begin(); a_iter != vertices[v_iter->first].adjList.end(); a_iter++ )
cout << " " << a_iter->first.value << " " << a_iter->second << endl;
cout << endl;
}
}
但是我收到以下错误:
错误1:
error C2440: 'initializing' : cannot convert from 'std::_Tree_const_iterator<_Mytree>' to 'std::_Tree_iterator<_Mytree>'
1> with
1> [
1> _Mytree=std::_Tree_val<std::_Tmap_traits<unsigned int,Vertex<unsigned int>,std::less<unsigned int>,std::allocator<std::pair<const unsigned int,Vertex<unsigned int>>>,false>>
1> ]
1> No constructor could take the source type, or constructor overload resolution was ambiguous
1> c:\users\user\desktop\cs m20a\topic g project 2\topic g project 2\graph.h(241) : while compiling class template member function 'void Graph<VertexType>::display(void) const'
1> with
1> [
1> VertexType=unsigned int
1> ]
错误2:
error C2678: binary '[' : no operator found which takes a left-hand operand of type 'const std::map<_Kty,_Ty>' (or there is no acceptable conversion)
1> with
1> [
1> _Kty=unsigned int,
1> _Ty=Vertex<unsigned int>
1> ]
1> c:\program files (x86)\microsoft visual studio 10.0\vc\include\map(164): could be 'Vertex<VertexType> &std::map<_Kty,_Ty>::operator [](unsigned int &&)'
1> with
1> [
1> VertexType=unsigned int,
1> _Kty=unsigned int,
1> _Ty=Vertex<unsigned int>
1> ]
1> c:\program files (x86)\microsoft visual studio 10.0\vc\include\map(209): or 'Vertex<VertexType> &std::map<_Kty,_Ty>::operator [](const unsigned int &)'
1> with
1> [
1> VertexType=unsigned int,
1> _Kty=unsigned int,
1> _Ty=Vertex<unsigned int>
1> ]
1> while trying to match the argument list '(const std::map<_Kty,_Ty>, const unsigned int)'
1> with
1> [
1> _Kty=unsigned int,
1> _Ty=Vertex<unsigned int>
1> ]
这是我的
Graph
类,如果有帮助的话。template <class VertexType>
class Graph
{
private:
// list of all vertices in the graph. assumes non-duplicate data.
map< VertexType, Vertex<VertexType> > vertices;
const unsigned MAX_VERTICES; // Maximum number of vertices the graph can hold.
unsigned numVertices; /** Current number of vertices in the graph. */
unsigned numEdges; /** Number of edges in the graph. */
typename map<VertexType, int>::iterator findEdge( const VertexType& v, const VertexType& w ) const;
public:
Graph( unsigned max );
unsigned getNumVertices() const;
unsigned getMaxNumVertices() const;
unsigned getNumEdges() const;
int getWeight( const VertexType& v, const VertexType& w ) const;
Graph<VertexType>& addVertex( const VertexType& newValue );
Graph<VertexType>& addEdge( const VertexType& v, const VertexType& w, int weight );
void removeEdge( const VertexType& v, const VertexType& w );
void BFS( const VertexType& v ) const;
void display() const;
}; // end Graph
最佳答案
您将方法声明为const
,也就是说,它不会更改任何成员变量:
void Graph<VertexType>::display() const
这意味着您只能使用底层成员变量的
const
方法;因此,您的基础类型为const_iterator
:typedef map<VertexType, Vertex<VertexType> >::const_iterator vertices_iter;
typedef map<Vertex<VertexType>, int>::const_iterator adjList_iter;
更好的是,如果您使用的是
C++11
,请利用auto
。至于第二个错误,我看不到是什么原因,但是,您无缘无故地进行查找工作:
for(auto a_iter = vertices[v_iter->first].adjList.begin();
a_iter != vertices[v_iter->first].adjList.end();
a_iter++ )
假设
v_iter
是原始循环中的vertices.begin()
。那么vertices[v_iter->first]
实际上与*v.begin()
相同。您可以将其替换为:for(auto a_iter = v_iter->first.adjList.begin();
a_iter != v_iter->first.adjList.end();
a_iter++ )