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)

#include<stdio.h>
#include<stdlib.h>

int n,v,i;
int e[100001][3],p[10001];
int r = 0;

int arrange(const void *,const void *);
int a(int );

int main()
{
  scanf("%d%d",&n,&v);

  for(i = 0;i <= n;i ++)
    {
      p[i] = i;
    }
	
  for(i = 0;i < v;i ++)
    {
      scanf("%d%d%d",&e[i][0],&e[i][1],&e[i][2]);
    }
	
  qsort(e,v,sizeof(int[3]),arrange);

  for(i = 0;i < v;i ++)
    {
      if(a(e[i][0])!=a(e[i][1]))
	{
	  r += e[i][2];
	  p[a(e[i][0])] = p[a(e[i][1])];
	}
    }
	
  printf("%d\n",r);
  return 0;
}

int arrange(const void *x,const void *y)
{
  return ((int*)x)[2] - ((int*)y)[2];
}


int a(int x)
{
  return p[x] == x?x:a(p[x]);
}