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())
}

Python: import heapq

def root(x):
    path_to_root = []
    while P[x] != x:
        path_to_root.append(x)
        x = P[x]
    for node in path_to_root:
        P[node] = x
    return x
def is_same_set(x,y):
    return root(x) == root(y)
def unite(x,y):
    P[root(x)] = root(y)

W = 0
N = int(input().strip())
P = [i for i in range(N)]
A = []
for i in range(N):
    v = list(map(int,input().strip().split(' ')))
    A.append(v)
edges = [] 
for i in range(N):
    for j in range(i,N):
        edge = [A[i][j],i,j]
        heapq.heappush(edges,edge)
while len(edges) > 0:
    e = heapq.heappop(edges)
    I = e[1]
    J = e[2]
    if e[0] != -1:
        if not is_same_set(I,J):
            unite(I,J)
            W += e[0]
print(W)

Python: # -*- coding: utf-8 -*-
from itertools import product

N = int(input())
INF = float("inf")
adj = []

for _ in range(N):
    adj.append([int(n) if n != "-1" else float("inf") for n in input().split()])

not_MST = list(range(1, N))
MST = [0]

cost = 0
while len(not_MST):
    tmp_min = INF
    tmp_idx = -1
    for m, n in product(MST, not_MST):
        if adj[m][n] < tmp_min:
            tmp_min = adj[m][n]
            tmp_idx = n
    MST.append(tmp_idx)
    not_MST.remove(tmp_idx)
    cost += tmp_min

print(cost)

Python: import heapq


class MST:
    """Given weighted graph, find minimum spanning tree.

    >>> mst = MST([[-1, 2, 3, 1, -1], \
                   [2, -1, -1, 4, -1], \
                   [3, -1, -1, 1, 1], \
                   [1, 4, 1, -1, 3], \
                   [-1, -1, 1, 3, -1]]);
    >>> mst.weight()
    5
    """
    MAX_WEIGHT = 2001

    def __init__(self, graph):
        self.graph = graph
        self.size = len(graph)
        self.tree = []
        self._search()

    def weight(self):
        return sum([self.graph[i][j] for i, j in self.tree])

    def _search(self):
        visited = [0]

        while len(visited) < self.size:
            h = []
            for node in visited:
                for i, w in enumerate(self.graph[node]):
                    if w == -1:
                        continue
                    if i in visited:
                        continue
                    heapq.heappush(h, (w, node, i))

            weight, src, dst = heapq.heappop(h)
            visited.append(dst)
            self.tree.append((src, dst))


def run():
    n = int(input())

    nodes = []
    for _ in range(n):
        nodes.append([int(i) for i in input().split()])

    mst = MST(nodes)
    print(mst.weight())


if __name__ == '__main__':
    run()

Python: N=int(input())
graph=[]
d=[2000]*(N)
p=[None]*(N)
color=["white"]*(N+1)
for i in range(N):
    a=list(map(int,input().split()))
    graph.append(a)
def prim():
    d[0]=0
    p[0]=-1
    while (True):
        mincost=2000
        for i in range(N):
            if color[i]!="black" and d[i]<mincost:
                mincost=d[i]
                u=i
        if mincost==2000:break
        color[u]="black"
        for v in range(N):
            if color[v]!="black" and graph[u][v]!=-1:
                if graph[u][v]<d[v]:
                    d[v]=graph[u][v]
                    p[v]=u
                    color[v]="gray"
prim()
print(sum(d))

Python: import sys

def readinput():
    n=int(input())
    nMat=[]
    for _ in range(n):
        m=list(map(int,input().split()))
        nMat.append(m)
    
    return n,nMat

WHITE=0
GRAY=1
BLACK=2
INFTY=sys.maxsize
def prim(n,nMat):

    color=[WHITE]*n
    d=[INFTY]*n
    p=[-1]*n

    d[0]=0
    p[0]=-1

    while True:
        mincost=INFTY
        for i in range(n):
            if color[i]!=BLACK and d[i] < mincost:
                mincost=d[i]
                u=i

        if mincost==INFTY:
            break

        # Tに属する頂点とV-Tに属する頂点をつなぐ辺の中で最小のコストのもの(u,p[u])が選ばれた
        color[u]=BLACK

        # V-Tに属する各頂点vとTに属する頂点をつなぐ辺の中で最小のコストのものが(v,p[v])でそのコストがd[v]
        # uがTに入ったことで辺(u,v)のコストとd[v]を比べてd[v]が大きかったらp[v]=u, d[v]=辺(u,v)のコストで更新
        for v in range(n):
            if color[v]!=BLACK and nMat[u][v]!=-1:
                if nMat[u][v]<d[v]:
                    d[v]=nMat[u][v]
                    p[v]=u
                    color[v]=GRAY
    return p,d


def main(n,nMat):
    p,d=prim(n,nMat)
    
    ans=0
    for i in range(n):
        if p[i] != -1:
            ans+=d[i]
    
    return ans

if __name__=='__main__':
    n,nMat=readinput()
    ans=main(n,nMat)
    print(ans)

Python: from heapq import heappush, heappop, heapify

N = int(input())
edges = [[] for i in range(N)]
for v in range(N):
    for w, c in enumerate(map(int, input().split())):
        if c != -1:
            edges[v].append((w, c))

visited = [0]*N
que = [(c, w) for w, c in edges[0]]
visited[0] = 1
heapify(que)

d=[0]+[10**9]*(N-1)

#左がコスト
ans = 0
while que:
    c, u = heappop(que)
    if visited[u]:
        continue
    visited[u] = 1
    d[u]=c
    for v, c in edges[u]:
        if visited[v]:
          continue
        heappush(que, (c, v))
print(sum(d))