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>
using namespace std;
static const int MAX = 100;
static const int INFTY = (1<<21);
static const int WHITE = 0;
static const int GRAY = 1;
static const int BLACK = 2;

struct Node{
  int color, dist, parent;
};

int n, M[MAX][MAX];
Node node[MAX];

void Printnodes(){
  string col[3] = {"WHITE", "GRAY ", "BLACK"};
  for(int i = 0; i < n; i++){
    cout << "nodeID : " << i ;
    cout << " color : " << col[node[i].color];
    cout << " parent : " << node[i].parent;
    cout << " dist : " << node[i].dist << endl;
  }
  cout << endl;
}

int main(){
  cin >> n;

  for(int i = 0; i < n; i++){
    for(int j = 0; j < n; j++){
      cin >> M[i][j];
    }
    node[i].color = WHITE;
    node[i].dist = INFTY;
    node[i].parent = -1;
  }

  int p = 0, totaldist = 0;;
  node[p].color = BLACK;
  node[p].dist = 0;

  while(true){
    //Printnodes();

    for(int i = 0; i < n; i++){
      if(M[p][i] > 0 && node[i].color != BLACK){
        node[i].dist = node[p].dist + M[p][i];
        node[i].parent = p;
        node[i].color = GRAY;
      }
    }

    int min_d = INFTY;
    p = -1;
    for(int i = 0; i < n; i++){
      if(node[i].dist < min_d && node[i].color != BLACK){
        min_d = node[i].dist;
        p = i;
      }
    }

    if(p == -1)
      break;

    node[p].color = BLACK;
    totaldist = node[p].dist;
    //cout << "node " << p << " turns to BLACK!" << endl;
    //cout << "Total distance is " << totaldist << endl;
  }

  cout << totaldist << endl;
  return 0;
}

C++: #include <iostream>
#include <vector>
#include <queue>

using namespace std;

using vi = vector<int>;
using vvi = vector<vi>;
using pii = pair<int, int>;

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define IN(v) int v;cin>>v;
#define OUT(v) cout<<v<<endl

int main() {
  IN(N);

  vvi A(N, vi(N, -1));
  REP(i, N) {
    REP(j, N) {
      IN(a);
      A[i][j] = a;
    }
  }
  priority_queue<pii, vector<pii>, greater<pii>> edge;
  REP(i, N) {
    if (A[0][i] != -1)
      edge.push(make_pair(A[0][i], i));
  }
  vector<bool> visited(N, false);
  visited[0] = true;
  int ans = 0;
  while (!edge.empty()) {
    pii p = edge.top(); edge.pop();
    if (visited[p.second])
      continue;
    visited[p.second] = true;
    ans += p.first;
    REP(i, N) {
      if (A[p.second][i] != -1 && !visited[i])
        edge.push(make_pair(A[p.second][i], i));
    }
  }
  OUT(ans);

  return 0;
}

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

static const int MAX=100;
static const int WHITE=0;
static const int GRAY=1;
static const int BLACK=2;

int n,M[MAX][MAX];

int prime(){
  int u,mincost;
  int d[MAX],p[MAX],color[MAX];

  for(int i=0;i<n;i++){
    d[i]=INT_MAX;
    p[i]=-1;
    color[i]=WHITE;
  }

  d[0]=0;

  while(1){
    mincost=INT_MAX;
    u=-1;
    for(int i=0;i<n;i++){
      if(color[i]!=BLACK&&d[i]<mincost){
	mincost=d[i];
	u=i;
      }
    }
 
    if(mincost==INT_MAX) break;
    
    color[u]=BLACK;

    for(int i=0;i<n;i++){
      if(color[i]!=BLACK&&M[u][i]!=INT_MAX){
	if(M[u][i]<d[i]){
	  d[i]=M[u][i];
	  p[i]=u;
	  color[i]=GRAY;
	}
      }
    }
  }

  int sum=0;
  for(int i=0;i<n;i++) sum+=d[i];

  return sum;
}

int main(){
  cin>>n;

  for(int i=0;i<n;i++){
    for(int j=0;j<n;j++){
      int e;
      cin>>e;
      if(e==-1) M[i][j]=INT_MAX;
      else M[i][j]=e;
    }
  }
  cout<<prime()<<endl; 
  return 0;
}