Go: package main

import (
	"bufio"
	"fmt"
	"log"
	"math"
	"os"
	"strconv"
	"strings"
)

type color int

const (
	white color = iota // 未訪問
	mst                // MSTとして確定
)

// 頂点
type node struct {
	matrix   []int // 隣接行列
	minToMst int   // MSTへの重み最小値
	parent   int   // 最小値の相手
	color    color
}

func main() {
	scanner := bufio.NewScanner(os.Stdin)
	n := eGetInt(scanner)

	nodes := make([]node, n)
	for i := 0; i < n; i++ {
		nodes[i].matrix = eAtoi((strings.Fields(eGetline(scanner))))
		nodes[i].parent = -1
		nodes[i].minToMst = math.MaxInt16
		nodes[i].color = white
	}

	// 初回はnode[0]がMSTに入るように,minToMstを設定
	nodes[0].minToMst = 0
	for { // 全部チェックするまで

		// どの頂点を新たにMSTに取り込むか
		min := math.MaxInt16
		u := -1
		for i := 0; i < n; i++ {
			if nodes[i].color == mst {
				continue
			}
			if nodes[i].minToMst < min {
				u = i
				min = nodes[i].minToMst
			}
		}

		if u == -1 {
			break
		}
		// MSTに追加する頂点決定
		nodes[u].color = mst

		// MSTに属していない頂点それぞれについて,MSTとの最小の重みを更新
		for i := 0; i < n; i++ {
			if nodes[i].color == mst {
				continue
			}
			if nodes[i].matrix[u] == -1 {
				// 接してない
				continue
			}
			if nodes[i].matrix[u] < nodes[i].minToMst {
				// node[u]との重みが最小
				nodes[i].minToMst = nodes[i].matrix[u]
				nodes[i].parent = u
			}
		}
	}

	sum := 0
	for _, v := range nodes {
		// node[0]はparentが入っていない
		if v.parent != -1 {
			sum += v.matrix[v.parent]
		}
	}
	fmt.Println(sum)
}

func eGetInt(scanner *bufio.Scanner) int {
	t := eAtoi(strings.Fields(eGetline(scanner)))
	return t[0]
}

func eGetline(p *bufio.Scanner) string {
	if !p.Scan() {
		if err := p.Err(); err != nil {
			log.Fatal(err.Error())
		}
		return ""
	}
	return p.Text()
}

func eAtoi(s []string) []int {
	ints := make([]int, len(s))
	var err error
	for i, e := range s {
		ints[i], err = strconv.Atoi(e)
		if err != nil {
			log.Fatal(err.Error())
		}
	}
	return ints
}

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))

Python: graph_n=int(input())


edge_dict={}



for i in range(graph_n):
    tmp_row=list(map(int,input()))
    for j in range(graph_n):
        if(tmp_row[j]!=-1):
            try:
                edge_dict[tmp_row].append([i,j])
            except:
                edge_dict[tmp_row]=[[i,j]]

sorted_edge=sorted(edge_dict.items())
vertex_flag=[0]*graph_n

searched_vertex_num=0
cost=0

for edges in sorted_edge:
    for edge in edges[1]:
        if(vertex_flag[edge[0]]==0 and vertex_flag[edge[1]]==0):
            vertex_flag[edge[0]]=1
            vertex_flag[edge[1]]=1
            seached_vertex_num+=2
            cost+=edges[0]
            if(graph_n <=searched_vertex_num):
                break

        elif(vertex_flag[edge[0]]==0 and vertex_flag[edge[1]]==1):
            vertex_flag[edge[0]]=1
            vertex_flag[edge[1]]=1
            seached_vertex_num+=1
            cost+=edges[0]
            if(graph_n <=searched_vertex_num):
                break

        elif(vertex_flag[edge[0]]==1 and vertex_flag[edge[1]]==0):
            vertex_flag[edge[0]]=1
            vertex_flag[edge[1]]=1
            seached_vertex_num+=1
            cost+=edges[0]
            if(graph_n <=searched_vertex_num):
                break

    if(graph_n <=searched_vertex_num):
        break


print(cost)

Python: # -*- coding: utf-8 -*-
'''
所要時間は、分位であった。
'''
# ライブラリのインポート
#import re #正規表現
import sys
#import heapq
import bisect
#import collections
#import math

def main():
    n = int(input())
    X = [[] for i in range(n)]
    l = []
    for i, line in enumerate(sys.stdin):
        X[i] = list(line.strip("\n").split())
        for j in range(i,n):
            c = int(X[i][j])
            if c == -1:
                continue
            else:
                r = (c,i,j)
                bisect.insort(l, r)
    
    uf = UnionFind(n)
    k = 0
    ans = 0
    count = 0
    while(count < n):
        try: tmp = l[k]
        except: break
        x = tmp[1]
        y = tmp[2]
        if not uf.same(x,y):
            uf.unite(x, y)
            ans += tmp[0] 
            count += 0
        k += 1
    print(ans)

class UnionFind:
    def __init__(self,n):
        self.p = [i for i in range(n)]
        return
    
    def root(self,x):
        while(1):
            if (self.p[x] == x): break
            y = x
            x = self.p[x]
            self.p[y] = self.p[x]
        return x

    def unite(self ,x, y):
        rx = self.root(x)
        ry = self.root(y)
        if rx == ry: return
        else:
            self.p[rx] = ry
            return 
    
    def same(self, x, y):
        rx = self.root(x)
        ry = self.root(y)
        return rx == ry


    
if __name__ == '__main__':
    main()

Python: # -*- coding: utf-8 -*-
"""
Created on Sat Sep 22 11:44:37 2018
ALDS1-12-A
@author: maezawa
"""
import heapq

n = int(input())
amat = [[] for _ in range(n)]
for i in range(n):
    amat[i] = list(map(int, input().split()))

adj = [[] for _ in range(n+1)]
for i in range(n):
    for j in range(i, n):
        if amat[i][j] == -1:
            continue
        adj[i+1].append([amat[i][j], j+1])
        adj[j+1].append([amat[j][i], i+1])

#print(adj)
d = [10**10]*(n+1)
h = []
heapq.heappush(h, [0, 1]) # [cost, node]
visited = [False]*(n+1)
while h:
    cost, node = heapq.heappop(h)
    if visited[node] == False and cost < d[node]:
        d[node] = cost
        visited[node] = True
        for nextnode in adj[node]:
            if visited[nextnode[1]]:
                continue
            heapq.heappush(h,nextnode)

d.pop(0)
print(sum(d))

Python: MAX = 2001


def prim(tree: [int], adjacent_list: [[int]]):
    cost = 0
    next = 0
    for l in adjacent_list:
        l[next] = MAX
    while True:
        tree.append(next)
        min_list = list()
        for t in tree:
            min_list.append(min([(v, i) for i, v in enumerate(adjacent_list[t])]))
        min_cost, i = min(min_list)
        if min_cost == MAX:
            return cost
        cost += min_cost
        for l in adjacent_list:
            l[i] = MAX
        next = i


if __name__ == '__main__':
    N = int(input())
    adjacent_list = [[int(e) if int(e) != -1 else MAX for e in input().rstrip().split()] for _ in range(N)]
    test_list = []
    print(prim(test_list, adjacent_list))