解题思路

• 每条边的边权可选，由颜色决定
• 同一颜色的线路可以直达
• 颜色最多有种
• 考虑将颜色视作链接点，进行分层图跑最短路
• 
• 最终结果除2
• 最多建条边
• （直接存状态Map跑最短路被毙掉了）

import java.io.*;
import java.math.BigInteger;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Objects;
import java.util.PriorityQueue;
import java.util.Stack;
import java.util.StringTokenizer;
import java.util.TreeSet;
import java.util.Vector;








//implements Runnable
public class Main{
	static long md=(long)20020219;
	static long Linf=Long.MAX_VALUE/2;
	static int inf=Integer.MAX_VALUE/2;
	static int M=200000;
	static int N=300;
	static int n=0;
	static int m=0;
	static int k=0;
	
	static
	class Node{
		int x;
		int y;
		public Node(int u,int v) {
			x=u;
			y=v;
		}
	}
	static
	class Edge{
		int fr,to,nxt;
		int val;
		public Edge(int u,int v,int w) {
			fr=u;
			to=v;
			val=w;
		}
	}
	static Edge[] e=new Edge[4*M+1];
	static int[] head;
	static int cnt=0;
	static int col=0;
	static void addEdge(int fr,int to,int val) {
		cnt++;
		e[cnt]=new Edge(fr, to, val);
		e[cnt].nxt=head[fr];
		head[fr]=cnt;
	}
	static int Dij(int s,int t) {
		int[] dis=new int[n+col+1];
		Arrays.fill(dis, inf);
		boolean[] vis=new boolean[n+col+1];
		PriorityQueue<Node> q=new PriorityQueue<Node>((o1,o2)->{
			return o1.y-o2.y;
		});
		dis[s]=0;
		q.add(new Node(s,0));
		while(!q.isEmpty()) {
			Node now=q.peek();q.poll();
			int x=now.x;
			if(vis[x])continue;
			vis[x]=true;
			for(int i=head[x];i>0;i=e[i].nxt) {
				int v=e[i].to;
				int w=e[i].val;
				if(vis[v])continue;
				if(dis[v]>dis[x]+w) {
					dis[v]=dis[x]+w;
					q.add(new Node(v, dis[v]));
				}
			}
		}
		return dis[t];
	}
	public static void main(String[] args) throws Exception{
		AReader input=new AReader();
		PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));	
		int T=input.nextInt();
		while(T>0) {
			n=input.nextInt();
			m=input.nextInt();
			head=new int[n+m*2];
			cnt=0;
			HashMap<Integer, Integer> hs=new HashMap<Integer, Integer>();
			col=n;
			for(int i=1;i<=m;++i) {
				int u=input.nextInt();
				int v=input.nextInt();
				int c=input.nextInt();
				int x=0;
				if(hs.get(c)==null) {
					col++;x=col;
					hs.put(c, col);
				}else {
					x=hs.get(c);
				}
				addEdge(u, x, 1);
				addEdge(x, u, 1);
				addEdge(v, x, 1);
				addEdge(x, v, 1);
			}
			int s=input.nextInt();
			int t=input.nextInt();
			
			out.println(Dij(s, t)/2);
			T--;
		}
		out.flush();
	    out.close();
	}
//	public static final void main(String[] args) throws Exception {
//		  new Thread(null, new Main(), "线程名字", 1 << 27).start();
//	}
//		@Override
//		public void run() {
//			try {
//				//原本main函数的内容
//				solve();
//
//			} catch (Exception e) {
//			}
//		}
//	static 
//	class Node{
//		int x;
//		int y;
//		public Node(int u,int v) {
//			x=u;
//			y=v;
//		}
//		@Override
//	    public boolean equals(Object o) {
//	        if (this == o) return true;
//	        if (o == null || getClass() != o.getClass()) return false;
//	        Node may = (Node) o;
//	        return x == may.x && y==may.y;
//	    }
//
//	    @Override
//	    public int hashCode() {
//	        return Objects.hash(x, y);
//	    }
//	}
		static
		class AReader{ 
		    BufferedReader bf;
		    StringTokenizer st;
		    BufferedWriter bw;

		    public AReader(){
		        bf=new BufferedReader(new InputStreamReader(System.in));
		        st=new StringTokenizer("");
		        bw=new BufferedWriter(new OutputStreamWriter(System.out));
		    }
		    public String nextLine() throws IOException{
		        return bf.readLine();
		    }
		    public String next() throws IOException{
		        while(!st.hasMoreTokens()){
		            st=new StringTokenizer(bf.readLine());
		        }
		        return st.nextToken();
		    }
		    public char nextChar() throws IOException{
		        //确定下一个token只有一个字符的时候再用
		        return next().charAt(0);
		    }
		    public int nextInt() throws IOException{
		        return Integer.parseInt(next());
		    }
		    public long nextLong() throws IOException{
		        return Long.parseLong(next());
		    }
		    public double nextDouble() throws IOException{
		        return Double.parseDouble(next());
		    }
		    public float nextFloat() throws IOException{
		        return Float.parseFloat(next());
		    }
		    public byte nextByte() throws IOException{
		        return Byte.parseByte(next());
		    }
		    public short nextShort() throws IOException{
		        return Short.parseShort(next());
		    }
		    public BigInteger nextBigInteger() throws IOException{
		        return new BigInteger(next());
		    }
		    public void println() throws IOException {
		        bw.newLine();
		    }
		    public void println(int[] arr) throws IOException{
		        for (int value : arr) {
		            bw.write(value + " ");
		        }
		        println();
		    }
		    public void println(int l, int r, int[] arr) throws IOException{
		        for (int i = l; i <= r; i ++) {
		            bw.write(arr[i] + " ");
		        }
		        println();
		    }
		    public void println(int a) throws IOException{
		        bw.write(String.valueOf(a));
		        bw.newLine();
		    }
		    public void print(int a) throws IOException{
		        bw.write(String.valueOf(a));
		    }
		    public void println(String a) throws IOException{
		        bw.write(a);
		        bw.newLine();
		    }
		    public void print(String a) throws IOException{
		        bw.write(a);
		    }
		    public void println(long a) throws IOException{
		        bw.write(String.valueOf(a));
		        bw.newLine();
		    }
		    public void print(long a) throws IOException{
		        bw.write(String.valueOf(a));
		    }
		    public void println(double a) throws IOException{
		        bw.write(String.valueOf(a));
		        bw.newLine();
		    }
		    public void print(double a) throws IOException{
		        bw.write(String.valueOf(a));
		    }
		    public void print(char a) throws IOException{
		        bw.write(String.valueOf(a));
		    }
		    public void println(char a) throws IOException{
		        bw.write(String.valueOf(a));
		        bw.newLine();
		    }
		}
	}