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<string.h>
#include<stdlib.h>
#include<math.h>
#include<stack>
#include<queue>
#include<vector>
#include<algorithm>
#include<string>
#include<iostream>
#include<set>
#include<map>
#include<bitset>

using namespace std;
typedef long long ll;
#define i_7 1000000007
#define i_5 1000000005

ll mod(ll a){
    ll c=a%i_7;
    if(c>=0)return c;
    else return c+i_7;
}
typedef pair<int,int> i_i;
typedef pair<ll,ll> l_l;
ll inf=1000000000000;/*10^12*/
#define rep(i,l,r) for(ll i=l;i<=r;i++)
ll max(ll a,ll b){if(a<b)return b;else return a;}
ll min(ll a,ll b){if(a>b)return b;else return a;}


//////////////////////////////////////
#define MAX_N 1000000//調節！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！
int par[MAX_N],dep[MAX_N];//depはrankのこと
//n要素で初期化
void init(int n){
    for(int i=0;i<=n-1;i++){
        par[i]=i;
        dep[i]=0;
    }
}
//木の根を求める
int find(int x){
    return par[x]==x?x:par[x]=find(par[x]);
}
//xとyの属する集合を併合
void unite(int x,int y){
    x=find(x);
    y=find(y);
    if(x==y)return;
    if(dep[x]<dep[y]){
        par[x]=y;
    }else{
        par[y]=x;
        if(dep[x]==dep[y])dep[x]++;
    }
}
//xとyが同じ集合に属するか否か
bool same(int x,int y){
    return find(x)==find(y);
}
//////////////////////////////////////
struct edge{int u,v,cost;};
bool comp(const edge& e1,const edge& e2){
    return e1.cost<e2.cost;
}
#define MAX_E 1000000//調節！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！
edge es[MAX_E];
int v,e;//頂点数vと辺数e

int kruskal(){
    sort(es,es+e,comp);
    init(v);
    int res=0;
    for(int i=0;i<e;i++){
        edge e=es[i];
        if(!same(e.u,e.v)){
            unite(e.u,e.v);
            res+=e.cost;
        }
    }
    return res;
}
///////////////////////////////////////////

int main(){
    cin>>v>>e;
    rep(i,0,e-1){
        cin>>es[i].u>>es[i].v>>es[i].cost;
    }
    cout<<kruskal()<<endl;
    
    return 0;
}