Dijkstra算法实现类—提高，邻接表+优先队列

总觉得前点时间写的Dijkstra，有点繁琐，还是用回邻接表和优先队列感觉舒服点。

废话就不多说了，原先那篇邻接矩阵的Dijkstra链接如下：http://blog.csdn.net/betabin/article/details/7375803

这次改为优先队列，则需要一个Vertex结构，记录其序号及到起点的cost。每次push进去队列之前，都刷新其最新cost。并且加了些辅助变量，如判断是否已经处理过该节点的bool数组等。改用邻接表的话，则是感觉空间比较好，感觉也是比较舒服。

这次的代码如下：

#include <iostream>#include <queue>#define MAX_EDGE 30#define MAX_VERTEX 10#define INFINITE 0x7fffffff#define AL_END -1using namespace std;struct Vertex {int vertex;int cost;};bool operator < (const Vertex &a, const Vertex &b){return a.cost > b.cost;}struct AlEdge {int next;int vertex;int cost;};class AlGraph{public:int source;int destination;int edgeNum;int vertexNum;int allCost;void Dijkstra();private:AlEdge edge[MAX_EDGE];priority_queue<Vertex> nextVertexQueue;int alVertex[MAX_VERTEX];bool vertexDealed[MAX_VERTEX];void initialize();void geteData();};void AlGraph::geteData(){cout << "Please input the number of vertex: ";cin >> vertexNum;cout << "Please input the number of edge: ";cin >> edgeNum;cout << "Please input the source: ";cin >> source;cout << "Please input the destination: ";cin >> destination;cout << "Please input the edges.(source, destination, cost.)" << endl;int s, d, c;int ip = 0;for (int i = 0; i < edgeNum; i++){cin >> s >> d >> c;edge[ip].next = alVertex[s];edge[ip].vertex = d;edge[ip].cost = c;alVertex[s] = ip++;}}void AlGraph::initialize(){memset(alVertex, AL_END, sizeof(alVertex));memset(vertexDealed, 0, sizeof(vertexDealed));allCost = 0;while (!nextVertexQueue.empty()){nextVertexQueue.pop();}geteData();}void AlGraph::Dijkstra(){initialize();Vertex currentVertex;currentVertex.cost = 0;currentVertex.vertex = source;nextVertexQueue.push(currentVertex);while (!nextVertexQueue.empty()){currentVertex = nextVertexQueue.top();nextVertexQueue.pop();if (currentVertex.vertex == destination){break;}if (vertexDealed[currentVertex.vertex]){continue;}vertexDealed[currentVertex.vertex] = true;Vertex nextVertex;for (int i = alVertex[currentVertex.vertex]; i != AL_END; i = edge[i].next){if (!vertexDealed[edge[i].vertex]){nextVertex.vertex = edge[i].vertex;nextVertex.cost = currentVertex.cost + edge[i].cost;nextVertexQueue.push(nextVertex);}}}if (currentVertex.vertex == destination){allCost = currentVertex.cost;}else{allCost = INFINITE;}}int main(){AlGraph test;test.Dijkstra();cout << "The smallest cost is: " << test.allCost << endl;return 0;}