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(shortestList)
	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++: // プリム法 最小全域木 Minimum Spanning Tree
#include <iostream>
#include <cstring>
#include <algorithm>
#include <queue>
#include <stack>
#include <cstdio>
#include <cstdlib>
#include <vector>
using namespace std;
static const int MAX = 100;
static const int INF = (1<<21);
static const int WHITE = 0;
static const int GRAY = 1;
static const int BLACK = 2;

int n, M[MAX][MAX]; //M:隣接行列

int prim() {
    int u, minv;
    int distance[MAX], parent[MAX], color[MAX];

    for(int i = 0; i < n; i++) {
        distance[i] = INF;
        parent[i] = -1;
        color[i] = WHITE;
    }

    distance[0] = 0;

    while (true) {
        minv = INF;
        u = -1;
        for(int i = 0; i < n; i++) {
            if (minv > distance[i] && color[i] != BLACK) {
                u = i;
                minv = distance[i];
            }
        }

        if (u == -1)
            break;

        color[u] = BLACK;
        for(int v = 0; v < n; v++) {
            if (color[v] != BLACK && M[u][v] != INF) {
                if (distance[v] > M[u][v]) {
                    distance[v] = M[u][v];
                    parent[v] = u;
                    color[v] = GRAY;
                }
            }
        }
    }

    int sum = 0;
    for(int i = 0; i < n; i++) {
        if (parent[i] != -1)
            sum  += M[i][parent[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) ? INF : e;
        }
    }

    cout << prim() << endl;
    
    return 0;
}

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

using namespace std;

// calculate Minimum Spanning Tree with Prim's algorithm
void mst(vector<vector<int>>& g, vector<int>& weights) {
    int n_vertex = weights.size();
    vector<bool> mst(n_vertex, false);

    weights[0] = 0;
    while (true) {
        int idx;
        int min_weight = INT_MAX;
        for (int i = 0; i < n_vertex; ++i) {
            if (!mst[i] && weights[i] < min_weight) {
                idx = i;
                min_weight = weights[i];
            }
        }

        if (min_weight == INT_MAX)
            break;

        mst[idx] = true;

        for (int i = 0; i < n_vertex; ++i) {
            if (!mst[i] && g[idx][i] != -1)
                weights[i] = min(weights[i], g[idx][i]);
        }
    }
}

int main() {
    int n;
    cin >> n;

    vector<vector<int>> g(n, vector<int>(n, 0));
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < n; ++j)
            cin >> g[i][j];
    }

    vector<int> weights(n, INT_MAX);
    mst(g, weights);

    int sum_of_weights = 0;
    for (int i = 0; i < n; ++i)
        sum_of_weights += weights[i];
    cout << sum_of_weights << '\n';
}

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

const int N = 100;
int n;
int A[N][N];
bool visit[N] = {0};
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];
		}
	}

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

	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 << -cost << endl;
		
	return 0;
}

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

const int N = 100;
int n;
int A[N][N];
bool visit[N] = {0};
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];
		}
	}

	Q.push(pair<int, int>(0,0));
	visit[0] = true;

	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 << -cost << endl;
		
	return 0;
}