Go: package main

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

const (
	MAX_N      = 200
	MAX_WEIGHT = 2000
)

type Edge struct {
	start  int
	end    int
	weight int
}

type ShortestInfo struct {
	edges    []Edge
	shortest int
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)

	n, err := nextInt(sc)
	if err != nil {
		panic(err)
	}

	shortestList := make([]ShortestInfo, n)
	for i := 1; i < n; i++ {
		shortestList[i] = ShortestInfo{edges: []Edge{}, shortest: MAX_N*MAX_WEIGHT + 1}
	}

	adjacentMatrix := make([][]int, n)
	for i := 0; i < n; i++ {
		adjacentMatrix[i] = make([]int, n)
		for j := 0; j < n; j++ {
			v, err := nextInt(sc)
			if err != nil {
				panic(err)
			}
			adjacentMatrix[i][j] = v
		}
	}

	mst([]int{1}, shortestList, adjacentMatrix)
	fmt.Println(calculateMinWeight(shortestList))
}

func calculateMinWeight(shortestList []ShortestInfo) int {
	visitedList := make([]bool, len(shortestList))
	visitedList[0] = true
	sumWeight := 0
	for !visitedAll(visitedList) {
		shortestInfo := shortestList[0]
		shortestList = shortestList[1:]
		edges := shortestInfo.edges
		for _, edge := range edges {
			if !visitedList[edge.end-1] {
				visitedList[edge.end-1] = true
				sumWeight += edge.weight
			}
		}
	}
	return sumWeight
}

func visitedAll(visitedList []bool) bool {
	for _, v := range visitedList {
		if !v {
			return false
		}
	}
	return true
}

func mst(nodeStack []int, shortestList []ShortestInfo, adjacentMatrix [][]int) {
	for len(nodeStack) > 0 {
		currentNode := nodeStack[0]
		nodeStack = nodeStack[1:]
		currentShortest := getShortest(currentNode, shortestList)
		adjacents := findAdjacents(currentNode, adjacentMatrix)
		for i := 0; i < len(adjacents); i++ {
			adj := adjacents[i]
			s := getShortest(adj.end, shortestList)
			if currentShortest.shortest+adj.weight < s.shortest || (currentShortest.shortest+adj.weight == s.shortest && len(currentShortest.edges)+1 > len(s.edges)) {
				setShortest(adj.end, adj, currentShortest, shortestList)
				nodeStack = append(nodeStack, adj.end)
			}
		}
	}
}

func getShortest(node int, shortestList []ShortestInfo) ShortestInfo {
	return shortestList[node-1]
}

func setShortest(node int, edge Edge, currentShortest ShortestInfo, shortestList []ShortestInfo) {
	newEdges := make([]Edge, len(currentShortest.edges)+1)
	for i := 0; i < len(newEdges)-1; i++ {
		newEdges[i] = currentShortest.edges[i]
	}
	newEdges[len(newEdges)-1] = edge
	shortestInfo := ShortestInfo{edges: newEdges, shortest: currentShortest.shortest + edge.weight}
	shortestList[node-1] = shortestInfo
}

func findAdjacents(currentNode int, adjacentMatrix [][]int) []Edge {
	adjacents := adjacentMatrix[currentNode-1]
	edges := []Edge{}
	for i, v := range adjacents {
		if v > 0 {
			edges = append(edges, Edge{start: currentNode, end: i + 1, weight: v})
		}
	}
	return edges
}

func nextInt(sc *bufio.Scanner) (int, error) {
	sc.Scan()
	return strconv.Atoi(sc.Text())
}

C++: #include <iostream>
#include <algorithm>
#include <vector>
#include <utility>

using namespace std;

int P[10001];

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

int root(int a) {
	if (P[a] == a)
		return a;
	return (P[a] = root(P[a]));
}

bool is_same_set(int a, int b) {
	return root(a) == root(b);
}

void unite(int a, int b) {
	P[root(a)] = root(b);
}

bool span(int n) {
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++) {
			if (!is_same_set(i, j))
				return false;
		}
	}
	return true;
}

int main() {
	int n;
	cin >> n;
	init(n);
	vector<vector<int> > map(n, vector<int>(n));
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++) {
			cin >> map[i][j];
		}
	}
	vector<pair<int, pair<int, int> > > edges;
	for (int i = 0; i < n; i++) {
		for (int j = i; j < n; j++) {
			if (map[i][j] >= 0)
				edges.push_back(pair<int, pair<int, int> >(map[i][j], pair<int, int>(i, j)));
		}
	}
	sort(edges.begin(), edges.end());
	int result = 0;
	while (!span(n)) {
		pair<int, pair<int, int> > edge = edges.front();
		edges.erase(edges.begin());
		int a = edge.second.first;
		int b = edge.second.second;
		if (!is_same_set(a, b)){
			unite(a, b);
			result += edge.first;
		}
	}
	cout << result << endl;
}

C++: #include<iostream>
#include<cstdio>
#include<cstring>
#include<vector>
#include<queue>
#include<set>
using namespace std;

struct Edge{
  int src,dst;
  int weight;

  Edge(int src,int dst,int weight):
    src(src),dst(dst),weight(weight){}
};

bool operator < (const Edge &m,const Edge &n){
  return m.weight != n.weight ? m.weight > n.weight :
    m.src != n.src ? m.src < n.src : m.dst < n.dst;
}

typedef vector<Edge> Edges;
typedef vector<Edges> Graph;

int MST(priority_queue<Edge>,int);
bool check(int[][100],int,int,int);//src,dstで結ばれる線を追加した時、グラフは閉路かどうかのチェック関数

int main(int argc,char* argv[]){
  int n,val;
  priority_queue<Edge> que;

  cin>>n;
  for(int i=1;i<=n;i++){
    for(int j=1;j<=n;j++){
      cin>>val;
      que.push(Edge(i,j,val));
    }
  }

  cout<<MST(que,n)<<endl;
  return 0;
}

int MST(priority_queue<Edge> que,int n){
  int ans=0;
  int flag[100][100];
  set<int> s;
  memset(flag,0,sizeof(flag[100][100]));

  while((int)s.size()!=n){
    Edge tmp(0,0,0);
    int ftmp[100][100];
    tmp=que.top();que.pop();
    memcpy(ftmp,flag,sizeof(flag));

    if(tmp.weight!=-1 && flag[tmp.src][tmp.dst]!=1){
      if(check(ftmp,tmp.src,tmp.dst,n)){
	flag[tmp.src][tmp.dst]=1;flag[tmp.dst][tmp.src]=1;
	s.insert(tmp.src);s.insert(tmp.dst);
	ans+=tmp.weight;
      }
    }
  }
  return ans;
}

bool check(int flag[][100],int src,int dst,int n){
  flag[src][dst]=1;
  queue<int> que;
  que.push(src);
  while(!que.empty()){
    int tmp=que.front();que.pop();

    for(int i=1;i<=n;i++){
      if(flag[tmp][i]==1){
	flag[tmp][i]=0;flag[i][tmp]=0;
	que.push(i);
      }
    }
    if(que.front()==src)
      return false;
  }

  return true;
}

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

const int N = 100;
int n;
int A[N][N];
priority_queue< pair<int, int> > Q;

int main()
{
	cin >> n;
	for (int i=0; i<n; i++)
	{
		for (int j=0; j<n; j++)
		{
			cin >> A[i][j];
		}
	}

	int mcost = -INT_MAX;

	for (int i=0; i<n; i++)
	{
		bool visit[N] = {0};

		Q.push(pair<int, int>(0,i));

		int cost = 0;

		while (Q.size())
		{
			pair<int, int> q = Q.top();
			Q.pop();
			int k = q.second;
			if (visit[k]) continue;
			cost += q.first;
			visit[k]=true;
			for(int j=0;j<n;j++)
			{
				int c = A[k][j];
				if (c <= 0) continue;
				if (visit[j]) continue;
				Q.push(pair<int, int>(-c,j));
			}
		}

//		cout << i << ' ' << -cost << endl;

		if (mcost < cost) mcost = cost;
	}

	cout << -mcost << endl;
		
	return 0;
}