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<cstdio>
#include<algorithm>
#include<iostream>
#include<string>

using namespace std;


struct edge {int u,v,cost;};
edge cookies[100000000];

int V,E;
int par[1000000],rank[10000000];

void init(int n){
  for(int i=0;i<n;i++){
    par[i]=i;
    rank[i]=0;
  }
}

int find(int x){
  if(par[x]==x){
    return x;
  } else {
    return par[x]=find(par[x]);
  }
}

void unite(int x,int y){
  x=find(x);
  y=find(y);
  if(x==y) return;

  if(rank[x]<rank[y]){
    par[x]=y;
  } else {
    par[y]=x;
    if(rank[x]==rank[y]) rank[x]++;
  }
}

bool same(int x,int y){
  return find(x)==find(y);
}

bool comp(const edge& e1,const edge& e2){
  return e1.cost<e2.cost;
}

int kruskal(){
  sort(cookies,cookies+E,comp);
  init(V);
  int res=0;

  for(int i=0;i<E;i++){
    edge e=cookies[i];
    if(!same(e.u,e.v)){
      unite(e.u,e.v);
      res+=e.cost;
    }
  }
  return res;

}


int main(){
  scanf("%d%d",&V,&E);
  for(int i=0;i<E;i++){
    scanf("%d%d%d",&cookies[i].u,&cookies[i].v,&cookies[i].cost);
  }


  printf("%d\n",kruskal());

  return 0;

}