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++: // 最小全域木
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<stack>
#include<algorithm>
#include<iostream>
#include<cmath>
#include<vector>

#include<queue>

using namespace std;

#define MAX_N 100
// 値の定義
const int INV = -1;
//const int EXIST = 1;
//const int NO_EXIST = 0;

// グラフ情報を保持する配列
int ary_graph[MAX_N + 1][MAX_N + 1];

// 辺の重みの最小値を保持する配列
// ( 頂点に入力される辺に対しての値 )
int ary_MinEdgeWeight[MAX_N + 1];

int n = 0;

void MinimumSpanningTree(int start_vertex);

int main(void)
{
    int sum = 0;

    for(int i = 0; i < MAX_N + 1; i++)
    {
    	ary_MinEdgeWeight[i] = INV;

        for(int j = 0; j < MAX_N + 1; j++)
        {
            // 配列の初期化
            ary_graph[i][j] = INV;
        }
    }

    cin >> n;

    for(int i = 0; i < n; i++)
    {
        for(int j = 0; j < n; j++)
        {
            // 隣接行列の設定
            cin >> ary_graph[i][j];
        }
    }

    // 頂点１から最小全域木を探索する
    MinimumSpanningTree(0);

    // 結果の表示
    for(int i = 0; i < n; i++)
    {
        sum += ary_MinEdgeWeight[i];
    }

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

    return 0;
}

// 辺の重みを設定する関数
// s      : 辺の開始頂点
// t      : 辺の終了頂点
// weight : 辺の重み
void set_weight(int s, int t, int weight)
{

    if( ary_MinEdgeWeight[t] == INV )
    {
        // 辺の重みの初期値の設定
        ary_MinEdgeWeight[t] = weight;
    }
    else
    {
        if( ary_MinEdgeWeight[t] > ary_graph[s][t] )
        {
            // 辺の最小値の設定
            ary_MinEdgeWeight[t] = ary_graph[s][t];
        }
    }

    return;
}

// 最小全域木を探索する関数
// start_vertex : 起点となる頂点のNo.
void MinimumSpanningTree(int start_vertex)
{

    queue<int> Q;

    // 開始点の情報の設定
    Q.push(start_vertex);
    ary_MinEdgeWeight[start_vertex] = 0;

    while( !Q.empty() )
    {
        // キューの先頭要素を取得して, 削除する
        int u = Q.front();
        Q.pop();

        for(int i = 0; i < n; i++)
        {
            // 隣接点を全て検索する
            int weight = ary_graph[u][i];

            if( weight != INV )
            {

                // 辺の重みを設定する
                set_weight(u, i, weight);
                //set_weight(i, u, weight);

                // キューにプッシュする
                Q.push(i);

                // 同じ辺を繰り返し辿らないように無効化する
                ary_graph[u][i] = INV;
                //ary_graph[i][u] = INV;
            }
        }
    }

    return;
}

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;
int n, M[MAX][MAX];
int prim() {
	int u, minv;
	int d[MAX], p[MAX], color[MAX];
	for (int i = 0; i<n; i++) {
		d[i] = INFTY;
		p[i] = -1;
		color[i] = WHITE;
	}
	d[0] = 0;
	while (1) {
		minv = INFTY;
		u = -1;
		for (int i = 0; i<n; i++) {
			if (minv!=d[i] && color[i] != BLACK) {
				u = i;
			}
		}
		if (u == -1)break;
		color[u] = BLACK;
		for (int v = 0; v<n; v++) {
			if (color[v] != BLACK&&M[u][v] != INFTY) {
				if (d[v]>M[u][v]) {
					d[v] = M[u][v];
					p[v] = u;
					color[v] = GRAY;
				}
			}
		}
	}
	int sum = 0;
	for (int i = 0; i<n; i++) {
		if (p[i] != -1)sum += M[i][p[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;
			M[i][j] = (e == -1) ? INFTY : e;
		}
	}
	cout << prim() << endl;
	return 0;
}

C++: #include<iostream>
using namespace std;
static const int MAX=100;
static const int INFTY=2000000000;
static const int WHITE=0;
static const int GRAY=1;
static const int BLACK=2;

int n,M[MAX+1][MAX+1];
int prim(){
    int u,minv;
    int d[MAX+1],p[MAX+1],color[MAX+1];
    for(int i=1;i<=n;i++){
        d[i]=INFTY;
        p[i]=-1;
        color[i]=WHITE;
    }
    d[1]=0;
    while(1){
        minv=INFTY;
        u=-1;
        for(int i=1;i<=n;i++){
            if(minv>d[i]&&color[i]!=BLACK){
                u=i;
                minv=d[i];
            }
        }
        if(u==-1)break;
        color[u]=BLACK;
        for(int v=1;v<=n;v++){
            if(color[v]!=BLACK&&M[u][v]!=INFTY){
                if(d[v]>M[u][v]){
                    d[v]=M[u][v];
                    p[v]=u;
                    color[v]=GRAY;
                }
            }
        }
    }
    int sum=0;
    for(int i=1;i<=n;i++){
        if(p[i]!=-1) sum+=M[i][p[i]];
    }
    return sum;
}
int main(){
    cin>>n;
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++){
            int e;
            cin>>e;
            M[i][j]=(e==-1)?INFTY:e;
        }
    }
    cout<<prim()<<"\n";
    return 0;
}