Main.java

 
import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;
 
/**
 *
 * @author cteam049
 */
public class Main {
 
    static class Node {
        Map<Integer, Node> sucs = new HashMap<Integer, Main.Node>();
        int value;
        int force;
 
        public Node(int value) {
            this.value = value;
        }
    }
 
    private static boolean appendNode(Node node, int i1, int i2, int i3) {
        if (node.value == i1) {
            Node n = new Node(i2);
            n.force = i3;
            node.sucs.put(i2, n);
            return true;
        } else if (node.value == i2) {
            Node n = new Node(i1);
            n.force = i3;
            node.sucs.put(i1, n);
            return true;
        } else if (node.sucs.containsKey(i1)) {
            return appendNode(node.sucs.get(i1), i1, i2, i3);
        } else if (node.sucs.containsKey(i2)) {
            return appendNode(node.sucs.get(i2), i1, i2, i3);
        } else {
            for (Node tmp : node.sucs.values()) {
                if (appendNode(tmp, i1, i2, i3)) return true;
            }
        }
        return false;
    }
 
 
    private static void preorder(Node node) {
        System.out.println(node.value);
        for (Node n : node.sucs.values()) {
            preorder(n);
        }
 
    }
 
    private static int solve(Node node) {
        if (node.sucs.isEmpty()) {
            return node.force;
        }
        int sum = 0;
        for (Node n : node.sucs.values()) {
            sum += solve(n);
        }
        if (sum < node.force) {
            return sum;
        }
        return node.force;
    }
 
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String line = null;
        int n, c;
        while (sc.hasNext()) {
            n = sc.nextInt();
            c = sc.nextInt();
            Node n1 = new Node(c);
            n1.force = Integer.MAX_VALUE;
 
            for (int i=0 ; i<n-1 ; i++) {
                int i1 = sc.nextInt();
                int i2 = sc.nextInt();
                int i3 = sc.nextInt();
                appendNode(n1, i1, i2, i3);
            }
 
//            preorder(n1);
            System.out.println(solve(n1));
        }
    }
 
}