Fr.java

import java.util.ArrayList;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Scanner;
 
 
public class Fr {
 
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
 
		int n;
		int main;
		ArrayList<Node> nodes;
 
		int a;
		int b;
		int v;
		Node tempNode;
		Node father;
		while(sc.hasNextInt()){	
			a = 0;
			b = 0;
 
			n = sc.nextInt();
			nodes = new ArrayList<Node>(n+1);
			for (int i = 0; i < n+1; i++) {
				nodes.add(null);
			}
//			System.out.println(nodes.size());
			main = sc.nextInt();
			nodes.add(main, new Node(main, Integer.MAX_VALUE));
 
			for (int i = 0; i < n-1; i++) {
				a = sc.nextInt();
				b = sc.nextInt();
				v = sc.nextInt();
 
				father = nodes.get(a);
				if (father == null){
					tempNode = new Node(a, v);
					nodes.set(a, tempNode);
 
					father = nodes.get(b);
					father.addChild(tempNode);
				}else{
					tempNode = new Node(b, v);
					nodes.set(b, tempNode);
 
					father.addChild(tempNode);
				}
			}
 
			System.out.println(getNodeValue(nodes.get(main)));
		}
		sc.close();
	}
 
 
	static int getNodeValue(Node node){
		if (node.child.size() == 0){
			return node.value;
		}
 
		int sumV = 0;
		for (Node n : node.child) {
			sumV += getNodeValue(n);
		}
 
		if (node.value > sumV){
			node.value = sumV;
			return node.value;
		}
		return node.value;
	}
}
 
class Node{
	int id;
	int value;
	LinkedList<Node> child;
	Node ancestor;
 
	public Node(int id, int value) {
		super();
		this.id = id;
		this.value = value;
 
		child = new LinkedList<Node>();
//		this.ancestor = ancestor;
	}
 
	void addChild(Node node){
		this.child.add(node);
	}
 
}