单源最短路径分支限界法之java实现

public class Short {
 public static void main(String args[]){
 
  int n = 5;
  int[] prev = new int[n+1];
  int[] dist = {0,0,5000,5000,5000,5000};
  int[][] c = {{0,0,0,0,0,0},{0,0,2,3,5000,5000},
    {0,5000,0,1,2,5000},{0,5000,5000,0,9,2},
    {0,5000,5000,5000,0,2},{0,5000,5000,5000,5000,0}};
  /*
  int n = 4;
  int[] dist = {0,0,5000,5000,5000};
  int[][] c = {{0,0,0,0,0},{0,0,2,3,5000},{0,5000,0,1,2},{0,5000,5000,0,9},{0,5000,5000,5000,0}};
  
  */

  Graph g = new Graph(n,prev,c,dist);
  g.shortestPath(1);
  System.out.println(dist[n]);
 }
 
}

class MinHeapNode{

 int i;    //顶点编号
 int length;   //当前路长

}
//循环队列
class CirQueue{
  int size = 5000;    //定义队列长度为1000
  int front,rear;
  MinHeapNode data[] = new MinHeapNode[size];

  public CirQueue(){
   front = rear = 0;
  }
  
  //元素入队操作
  void queryIn(MinHeapNode e){
   
   if((rear +1)%size == front){
    System.out.println(“队列已满”);
   }else{
    rear = (rear+1)%size; //队尾指针在循环意义下加1
    data[rear] = e;   //在队尾插入元素
    
   }
  }
  
  
  //元素出队操作
  MinHeapNode queryOut(){
   if(rear == front){
    System.out.println(“队列已空”);
    return null;
   }else{
    front = (front+1)%size;  //队列在循环意义下加1
    return data[front];
   }
  }
  //读取队头元素,但不出队
  MinHeapNode getQuery(){
   if(rear == front){
    System.out.println(“队列已空”);
    return null;
   }else{
    return data[(front+1)%size];
   }
  }
  
  
  //判断队列是否为空
  boolean empty(){
   return front == rear;
   
  }
 }

//图的表示
class Graph{
 static int inf = 5000;   //两点距离上界
 int n;       //图的顶点个数
 int prev[];      //图的前驱顶点
 int c[][];      //图的邻接矩阵
 int dist[];      //最短距离数组
 public Graph(int n,int[] prev,int[][] c,int[] dist){
  
  this.n = n;
  this.prev = prev;
  this.c = c;
  this.dist  = dist;
 }
 
 /**
  * 单源最短路径问题的优先队列式分支限界法
  */
 
 public void shortestPath(int v){
  //创建队列
  CirQueue qq = new CirQueue();
  
  //定义源为初始扩展结点
  MinHeapNode e = new MinHeapNode();
  e.i = v;
  e.length = 0;
  dist[v] = 0;
  qq.queryIn(e);
  //搜索问题的解空间
  while(true){
   for(int j = 1;j<=n;j++){
    
    if(j>n){
     break;
    }
    MinHeapNode m = qq.getQuery();
    if((c[m.i][j]<inf)&&(m.length + c[m.i][j] < dist[j])){
     
     //顶点i到顶点j可达,且满足控制约束
     dist[j] = m.length + c[m.i][j];
     prev[j] = m.i;
    
    //加入活结点优先队列
    MinHeapNode mi = new MinHeapNode();
    mi.i = j;
    mi.length  = dist[j];
    
    qq.queryIn(mi);   //元素入队
    }
   }//for循环结束
   
   
   qq.queryOut();    //当该结点的孩子结点全部入队后,删除该结点
   
   if(qq.empty()){    //当队列为空时,算法结束
    break;
   }
  }//while循环结束
 }
}

    原文作者:分支限界法
    原文地址: https://blog.csdn.net/tpfbx/article/details/6480308
    本文转自网络文章,转载此文章仅为分享知识,如有侵权,请联系博主进行删除。
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