Go: // Find the minimum spanning tree by the Kruskal algorithm
// -------------------------------------------------------
// Kruskal(G):
//     A = ∅
//     foreach v ∈ G.V:
//        MAKE-SET(v)
//     foreach (u, v) in G.E ordered by weight(u, v), increasing:
//         if FIND-SET(u) ≠ FIND-SET(v):
//             A = A ∪ {(u, v)}
//             UNION(u, v)
//     return A
//
// Ref: https://en.wikipedia.org/wiki/Kruskal%27s_algorithm

package main

import (
	"bufio"
	"os"
	"sort"
	"strconv"
	"strings"
	"fmt"
	)

var scanner = bufio.NewScanner(os.Stdin)
var (
	matrix [][]int
)

type Edge struct {
	a, b, cost, added int
}
type ByCost []Edge

var edges ByCost

func (a ByCost) Len() int           { return len(a) }
func (a ByCost) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
func (a ByCost) Less(i, j int) bool { return a[i].cost < a[j].cost }

func main() {
	for scanner.Scan() {
		buf := strings.Split(scanner.Text(), " ")
		n, _ := strconv.Atoi(buf[0])
		m, _ := strconv.Atoi(buf[1])
		if n == 0 && m == 0 {
			break
		}
		matrix = make([][]int, n)
		for i := range matrix {
			matrix[i] = make([]int, n)
		}
		for i := 0; i < m; i++ {
			scanner.Scan()
			buf_ := strings.Split(scanner.Text(), " ")
			a, _ := strconv.Atoi(buf_[0])
			b, _ := strconv.Atoi(buf_[1])
			cost, _ := strconv.Atoi(buf_[2])
			matrix[a][b] = cost
			matrix[b][a] = cost
		}
		sum := Kruskal(n)
		fmt.Println(sum)
		if len(edges) > 0 {
			edges = []Edge{}
		}
	}
}

func Kruskal_func(size, edge_num int) int {
	for i := 0; i < size; i++ {
		for j := 0; j < size; j++ {
			if matrix[i][j] > 0 {
				tmp := Edge{i, j, matrix[i][j], 0}
				edges = append(edges, tmp)
			}
		}
	}
	sort.Sort(ByCost(edges))
	UF_Init(edge_num)
	for i := 0; i < edge_num; i++ {
		a := edges[i].a
		b := edges[i].b
		if UF_Find(a) != UF_Find(b) {
			edges[i].added = 1
			UF_Union(UF_Find(a), UF_Find(b))
		}
	}
	sum := 0
	for i := 0; i < edge_num; i++ {
		if edges[i].added != 0 {
			// log.Printf("edge(%d,%d) is added\n", edges[i].a, edges[i].b)
			sum += edges[i].cost
		}
	}
	return sum
}

func Kruskal(size int) int {
	edge_num := 0
	for i := 0; i < size; i++ {
		for j := 0; j < size; j++ {
			if matrix[i][j] > 0 {
				edge_num++
			}
		}
	}
	return Kruskal_func(size, edge_num)
}

/*** Union-Find functions ***/
var UF_Parent []int
var UF_Rank []int

func UF_Init(n int) {
	UF_Parent = make([]int, n)
	UF_Rank = make([]int, n)
	for i := 0; i < n; i++ {
		UF_Parent[i] = i
		UF_Rank[i] = 0
	}
}
func UF_Union(a, b int) {
	if UF_Rank[a] < UF_Rank[b] {
		UF_Parent[a] = b
	} else {
		UF_Parent[b] = a
	}
	if UF_Rank[a] == UF_Rank[b] {
		UF_Rank[a]++
	}
}
func UF_Find(a int) int {
	if UF_Parent[a] == a {
		return a
	}
	return UF_Find(UF_Parent[a])
}
/*** Union-Find functions ***/

C++: #include<cstdio>
#include<algorithm>
#include<iostream>
#include<vector>
#include<string>
#include<queue>

using namespace std;

#define reps(i,f,n) for(int i=f;i<int(n);i++)
#define rep(i,n) reps(i,0,n)

typedef vector<int> vi;
typedef vector<vi> vii;
typedef pair<int,int> pii;

class dii{
	public:
	int first;
	int second;
	dii(int f,int s):first(f),second(s){}
	bool operator<(const dii& d)const{
		if(d.first == first) return d.second<second;
		return d.first<first;
	}
};
int main(void){
	A:;
	
	int n,m;
	cin>>n>>m;
	if(n==0)return 0;
	
	vector<pii> edge[100];
	int st = -1;
	int stmin = 1000000000;
	rep(i,m){
		int a,b,c;
		cin>>a>>b>>c;
		edge[a].push_back(pii(b,c));
		edge[b].push_back(pii(a,c));
		
		if(c<stmin){
			stmin = c;
			st = a;
		}
	}
	
	priority_queue<dii> que;
	rep(i,edge[st].size()){
		que.push(dii(edge[st][i].second, edge[st][i].first));
	}
	
	int visit[101]={0};
	visit[st]=1;
	int ans = 0;
	while(1){
		if(que.empty())break;
		dii u = que.top();
		que.pop();
		
		if(visit[u.second]==1)continue;
		visit[u.second]=1;
		
		ans += u.first;
		
		rep(i,edge[u.second].size()){
			que.push(dii(edge[u.second][i].second, edge[u.second][i].first));
		}
	}
	
	printf("%d\n",ans);
	goto A;
}

C++: #include<cmath>
#include<cctype>
#include<cstdlib>
#include<cstdio>
#include<iostream>
#include<algorithm>
#include<vector>
#include<deque>
#include<string>
#include<queue>
#include<map>
#include<set>
#include<utility>
#include<queue>
 
const int MAXN = 100;
using namespace std;
bool visited[MAXN];
struct UnionFind {
  vector<int> data;
  UnionFind(int size) : data(size, -1) { }
  bool unionSet(int x, int y) {
    x = root(x); y = root(y);
    if (x != y) {
      if (data[y] < data[x]) swap(x, y);
      data[x] += data[y]; data[y] = x;
    }
    return x != y;
  }
  bool findSet(int x, int y) {
    return root(x) == root(y);
  }
  int root(int x) {
    return data[x] < 0 ? x : data[x] = root(data[x]);
  }
  int size(int x) {
    return -data[root(x)];
  }
};
struct edge{
  edge(int from,int to):from(from),to(to){}
  int from,to;
};
bool operator<(edge a,edge b){
  if(a.from != b.from)return a.from < b.from;
  else return a.to < b.to;
}
typedef pair<int,edge> P;
priority_queue<pair<int,edge>,vector<P>,greater<P> > que;
int main(){
  int n,m;
  while(cin >> n >> m && n + m != 0){
 
    for (int i = 0; i < m; ++i){
      int a,b,c;
      cin >> a >> b >> c;
      que.push(make_pair(c,edge(a,b)));
    }
    UnionFind u(m);
    int ans = 0;
    while(!que.empty()){
      edge e = que.top().second;
      int  cost= que.top().first;
      que.pop();
      if(!u.findSet(e.from,e.to)){
	ans += cost;
	u.unionSet(e.from, e.to);
      }
    }
    cout << ans << endl;
  }
  return 0;
}

C++: #include <iostream>
#include <vector>
#include <queue>
#include <utility>
using namespace std;

#define INF 1e9

int prim(vector<vector<pair<int, int> > > adjlist){
  int n = adjlist.size();
  vector<int> result(n, INF);
  int sum = 0;
  
  priority_queue<pair<int, int> > wait;
  wait.push(make_pair(0, 0));
  result[0] = 0;
  while(!wait.empty()){
    int nowcost = -wait.top().first;
    int nowpoint = wait.top().second;
    wait.pop();
    if(nowcost > result[nowpoint]){ continue; }

    sum += nowcost;
    result[nowpoint] = -INF;
    
    for(int i = 0; i < (int)adjlist[nowpoint].size(); i++){
      int nextcost = adjlist[nowpoint][i].first;
      int nextpoint = adjlist[nowpoint][i].second;
      if(result[nextpoint] > nextcost){
        result[nextpoint] = nextcost;
        wait.push(make_pair(-nextcost, nextpoint));
      }
    }
  }

  return sum;
}


int main(void){
  while(true){
    int n, m;
    cin >> n >> m;
    if(n == 0 && m == 0){ break; }
    
    int a, b, cost;
    vector<vector<pair<int, int> > > adjlist(n);
    for(int i = 0; i < m; i++){
      cin >> a >> b >> cost;
      adjlist[a].push_back(make_pair(cost, b));
      adjlist[b].push_back(make_pair(cost, a));
    }

    cout << prim(adjlist) << endl;
  }

  return 0;
}

C++: #include<stdio.h>
#include<string.h>
#include<math.h>
int main(void)
{
	int a,s,d[101],f[101],g[101],h,i,j,size[101],ban[101];
	int z,x,q;
	scanf("%d %d",&a,&s);
	for(i=0;i<a;i++){
		ban[i]=i;
		size[i]=1;
	}
	for(i=0;i<s;i++) scanf("%d %d %d",&d[i],&f[i],&g[i]);
	for(i=0;i<s;i++){
		if(d[i]>f[i]) h=d[i]; d[i]=f[i]; f[i]=h;
		for(j=i+1;j<s;j++){
			if(g[i]>g[j]){
				h=g[i]; g[i]=g[j]; g[j]=h;
				h=d[i]; d[i]=d[j]; d[j]=h;
				h=f[i]; f[i]=f[j]; f[j]=h;
			}
		}
	}
	/*for(i=0;i<s;i++)
		printf("%d %d %d\n",d[i],f[i],g[i]);*/
	for(i=0;i<s;i++){
	//	printf("%d %d %d\n\n",d[i],f[i],g[i]);
		z=d[i]; x=f[i];
		while(ban[z]!=z) z=ban[z];
		while(ban[x]!=x) x=ban[x];
		if(z!=x){
			q+=g[i];
			if(size[z]>=size[x]) ban[x]=z;
			else if(size[z]<size[x]) ban[z]=x;
			/*else{
				ban[x]=z;
				size[x]++;
			}*/
		}
	}
	printf("%d\n",q);
	return 0;
}