单源最短路径 贪心算法 java实现

public class Dijkstra {

static int MAX_SIZE=6;

public static void dijkstra(int v,float[][]a,float[]dist,int[]prev){

int n=dist.length-1;

if(v<1||v>n)return;

boolean []s=new boolean[n+1];

for(int i=1;i<=n;i++) {

dist[i]=a[v][i];

s[i]=false;

if(dist[i]==Float.MAX_V ALUE)

prev[i]=0;

else

prev[i]=v;

}

dist[v]=0;s[v]=true;

for(int i=1;i

float temp=Float.MAX_V ALUE;

int u=v;

for(int j=1;j<=n;j++)

if((!s[j])&&(dist[j]

u=j;

temp=dist[j];

}

s[u]=true;

for(int j=1;j<=n;j++)

if((!s[j])&&(a[u][j]

float newdist=dist[u]+a[u][j];

if(newdist

dist[j]=newdist;

prev[j]=u;

}

}

}

}

public static void main(String args[]){

float a[][]=new float[MAX_SIZE][MAX_SIZE];float[]dist=new float[MAX_SIZE];int []prev=new int[MAX_SIZE];

for(int i=0;i<6;i++)

for(int j=0;j<6;j++)

a[i][j]=Float.MAX_V ALUE;

a[1][2]=10;

a[1][4]=30;

a[1][5]=100;

a[2][3]=50;

a[3][5]=10;

a[4][3]=20;

a[4][5]=60;

int v=1;//假设从顶点1处出发

dijkstra(v,a,dist,prev);

System.out.println("从1出发到2、3、4、5的最短路径依次是:");

for(int j=2;j<6;j++){

System.out.println(dist[j]);

}

int z=prev[5],y=prev[z],x=prev[y];

System.out.println("从1到5最短路径经过的点为：");

System.out.print(x+" "+y+" "+z+" "+"5");

}

}