在idea实现

package medium;
import com.sun.source.tree.Tree;

import java.util.*;

class Interval {
int start;
int end;
}
public class TreeOfDiam {

public static void main(String[] args) {
      Interval[] Tree_edge = new Interval[5];
      for(int i = 0; i < Tree_edge.length;i++){
          Tree_edge[i] = new Interval();
      }
      Tree_edge[0].start = 0;
      Tree_edge[0].end = 1;
      Tree_edge[1].start = 1;
      Tree_edge[1].end = 5;
      Tree_edge[2].start = 1;
      Tree_edge[2].end = 2;
      Tree_edge[3].start = 2;
      Tree_edge[3].end = 3;
      Tree_edge[4].start = 2;
      Tree_edge[4].end = 4;
      int Edge_value[] = {3,4,2,1,5} ;
      solve(6,Tree_edge,Edge_value);
}
public static int[][] get_graph(int n,Interval[] Tree_edge,int[] Edge_value){
    int[][] graph = new int[n][n];
    for(int i = 0;i < n;i++){
        for(int j = 0;j < n;j++){
            if(i == j) graph[i][j] = 0;
            else graph[i][j] = 9999;
        }
    }
    for(int i = 0;i < Edge_value.length;i++){
        graph[Tree_edge[i].start][Tree_edge[i].end] = Edge_value[i];
        graph[Tree_edge[i].end][Tree_edge[i].start] = Edge_value[i];
    }
    return graph;
}
public static int solve (int n, Interval[] Tree_edge, int[] Edge_value) {
    // write code here
    int graph[][] = get_graph(n,Tree_edge,Edge_value);
    int[] distance = new int[n];
    for(int i = 0;i < n;i++){
        distance[i] = graph[0][i];
    }
    int[] flag = new int[n];
    flag[0] = 1;
    for(int i = 1;i < n;i++){
        int max = 0;
        int v = 0;
        for(int j = 1;j < n;j++){
            if(flag[j] == 0 && graph[i][j] > max && graph[i][j] != 9999 ){
                max = graph[i][j];
                v = j;
            }
        }
        flag[v] = 1;
        for(int k = 1;k < n;k++){
            if(distance[k] < distance[v] + graph[v][k] && graph[v][k] != 9999){
                distance[k] = distance[v] + graph[v][k];
                //System.out.println(distance[k]);
            }
        }
    }
    Arrays.sort(distance);
    System.out.println(distance[n - 1] - 9999);
    return distance[n - 1];
}

}