最小二叉树

/*
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 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package cn.iceson.mstapp;

/**
 *
 * @author lucky_ice
 */
public class StackX {
    private final int SIZE=20;
    private int[] st;
    private int top;
    public StackX(){
        st=new int[SIZE];
        top=-1;
    }
    public void push(int j){
        st[++top]=j;
    }
    public int pop(){
        return st[top--];
    }
    public int peek(){
        return st[top];
    }
    public boolean isEmpty(){
        return top==-1;
    }
}

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package cn.iceson.mstapp;

/**
 *
 * @author lucky_ice
 */
public class Vertex {
    public char label;
    public boolean wasVistied;
    public Vertex(char lab){
        this.label=lab;
        wasVistied=false;
    }
}

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package cn.iceson.mstapp;

/**
 *
 * @author lucky_ice
 */
public class Graph {
    private final int MAX_VERTS=20;
    private Vertex[] vertexlist;
    private int[][] adjMat;
    private int nVerts;
    private StackX theStack;
    public Graph(){
        vertexlist=new Vertex[MAX_VERTS];
        adjMat=new int[MAX_VERTS][MAX_VERTS];
        nVerts=0;
        for(int j=0;j<MAX_VERTS;j++){
            for(int k=0;k<MAX_VERTS;k++){
                adjMat[j][k]=0;
            }
        }
        theStack=new StackX();
    }
    public void addVertex(char lab){
        vertexlist[nVerts++]=new Vertex(lab);
    }
    public void addEdge(int start,int end){
        adjMat[start][end]=1;
        adjMat[end][start]=1;
    }
    public void displayVertex(int v){
        System.out.print(vertexlist[v].label);
    }
    public void mst(){
        vertexlist[0].wasVistied=true;
        theStack.push(0);
        while(!theStack.isEmpty()){
            int currentVertex=theStack.peek();
            int v=getAdjUnvisitedVertex(currentVertex);
            if(v==-1){
                theStack.pop();
            }else{
                vertexlist[v].wasVistied=true;
                theStack.push(v);
                displayVertex(currentVertex);
                displayVertex(v);
                System.out.print(" ");
            }
        }
        for(int i=0;i<nVerts;i++){
            vertexlist[i].wasVistied=false;
        }
    }
    public int getAdjUnvisitedVertex(int v){
        for(int i=0;i<nVerts;i++)
            if(adjMat[v][i]==1&&vertexlist[i].wasVistied==false)
                return i;
        return -1;
    }
}

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package cn.iceson.mstapp;

/**
 *
 * @author lucky_ice
 */
public class Test {
    public static void main(String[] args){
        Graph theGraph=new Graph();
        theGraph.addVertex('A');
        theGraph.addVertex('B');
        theGraph.addVertex('C');
        theGraph.addVertex('D');
        theGraph.addVertex('E');
        theGraph.addEdge(0, 1);
        theGraph.addEdge(0, 2);
        theGraph.addEdge(0, 3);
        theGraph.addEdge(0, 4);
        theGraph.addEdge(1, 2);
        theGraph.addEdge(1, 3);
        theGraph.addEdge(1, 4);
        theGraph.addEdge(2, 3);
        theGraph.addEdge(2, 3);
        theGraph.addEdge(3, 4);
        System.out.print("Minimun spanning tree:");
        theGraph.mst();
        System.out.println();
    }
}