Problem:
Minimum Spanning Tree

Find the sum of weights of edges of the Minimum Spanning Tree for a given weighted undirected graph G = (V, E).

Input

|V| |E|
s0 t0 w0
s1 t1 w1
:
s|E|-1 t|E|-1 w|E|-1

, where |V| is the number of vertices and |E| is the number of edges in the graph. The graph vertices are named with the numbers 0, 1,..., |V|-1 respectively.

si and ti represent source and target verticess of i-th edge (undirected) and wi represents the weight of the i-th edge.

Output

Print the sum of the weights of the Minimum Spanning Tree.

Constraints

1 ≤ |V| ≤ 10,000

0 ≤ |E| ≤ 100,000

0 ≤ wi ≤ 10,000

The graph is connected

There are no parallel edges

There are no self-loops

Sample Input 1

4 6
0 1 2
1 2 1
2 3 1
3 0 1
0 2 3
1 3 5

Sample Output 1

3

Sample Input 2

6 9
0 1 1
0 2 3
1 2 1
1 3 7
2 4 1
1 4 3
3 4 1
3 5 1
4 5 6

Sample Output 2

5

Solution in C# (judge verdict: Accepted)

using System;
using System.Linq;//リストの使用
using System.Collections.Generic;
class Program
{
static string[] input = Console.ReadLine().Split(' ');
static long v = long.Parse(input[0]);
static long e = long.Parse(input[1]);
static long[] parents = new long[v];//親
static long[][] edges = new long[e][];
static long answer = 0;
  
	static void Main()
	{
    for(long i = 1; i < v; i++)
    {
    parents[i] = i;
    }

    for(long i = 0; i < e; i++)
    {
      edges[i] = new long[3];
      string[] memo = Console.ReadLine().Split(' ');
      edges[i][0] = long.Parse(memo[0]);
      edges[i][1] = long.Parse(memo[1]);
      edges[i][2] = long.Parse(memo[2]);
    }
    Array.Sort(edges, (a, b) => a[2].CompareTo(b[2]));//長さでソート
    
    for(long i = 0; i < e; i++)//クラスカル法
    {
      if(whatParent(edges[i][0]) != whatParent(edges[i][1]))
      {
        parents[whatParent(edges[i][0])] = whatParent(edges[i][1]);//親を結合して統一。親が2人できることはない。
        answer += edges[i][2];
      }
    }
    Console.WriteLine(answer);
	}

  static long whatParent(long child)
  {
    if(parents[child] == child) return child;
    else return parents[child] = whatParent(parents[child]);
  }
  
}