Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

//util
var sc = bufio.NewScanner(os.Stdin)

func nextStr() string {
	sc.Scan()
	return sc.Text()
}

func nextInt() int {
	sc.Scan()
	i, e := strconv.Atoi(sc.Text())
	if e != nil {
		panic(e)
	}
	return i
}

func printList(list []int) {
	n := len(list)
	buf := bufio.NewWriter(os.Stdout)
	for _, v := range list[0 : n-1] {
		buf.Write([]byte(fmt.Sprintf("%d ", v)))
	}
	buf.Write([]byte(fmt.Sprintf("%d\n", list[n-1])))
	buf.Flush()
}

func max(a, b int) int {
	if a > b {
		return a
	} else {
		return b
	}
}

func min(a, b int) int {
	if a > b {
		return b
	} else {
		return a
	}
}

//solve
const (
	MAX   = 100
	INFTY = (1 << 21)
	WHITE = 0
	GRAY  = 1
	BLACK = 2
)

//V: グラフの頂点全体の集合
//T: MSTに属する頂点の集合
var (
	n     int
	M     [MAX][MAX]int //重みを記録する隣接行列
	color [MAX]int
	p     [MAX]int //MSTにおける頂点の親を記録
	d     [MAX]int //Tに属する頂点と、V−Tに属する頂点を繋ぐ辺の中で、重みが最小のものを記録
)

func prim() int {
	var u, minv int
	//初期化
	for i := 0; i < n; i++ {
		d[i] = INFTY
		p[i] = -1
		color[i] = WHITE
	}

	d[0] = 0

	for {
		//頂点uを決めていく
		//つまり、Tに属する頂点と、V−Tに属する頂点を繋ぐ辺の中で、重みが最小のものを決める
		minv = INFTY
		u = -1
		for i := 0; i < n; i++ {
			//未訪問かつ、辺の重みが最小となるuを選ぶ
			if minv > d[i] && color[i] != BLACK {
				u = i
				minv = d[i]
			}
		}

		if u == -1 {
			break
		}

		color[u] = BLACK
		for v := 0; v < n; v++ {
			//未訪問かつ、辺が存在するとき
			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
				}
			}
		}
	}

	sum := 0
	for i := 0; i < n; i++ {
		if p[i] != -1 {
			sum += M[i][p[i]]
		}
	}
	return sum
}

func main() {
	sc.Split(bufio.ScanWords)
	n = nextInt()

	for i := 0; i < n; i++ {

		for j := 0; j < n; j++ {
			tmp := nextInt()
			if tmp == -1 {
				tmp = INFTY
			}
			M[i][j] = tmp
		}

	}

	fmt.Println(prim())

}

Python: def prim(cost):
    sumcost=0
    V=len(cost)
    mincost=[float('inf')] * V
    used=[False] * V
    mincost[0]=0
    while True:
        v=-1
        for u in range(V):
            if not used[u] and (v==-1 or mincost[u]<mincost[u]):
                v=u
        if v==-1: break
        used[v]=True
        sumcost=sumcost+mincost[v]
        for u in range(V):
            if cost[u][v]==-1:
                continue
            mincost[u]=min(mincost[u],cost[v][u])
    return sumcost


n=int(raw_input())
A=[0]*n
for u in range(n):
    A[u]=map(int, raw_input().split())
 
result=prim(A)
print(result)

Python: import sys

def debug(x, table):
    for name, val in table.items():
        if x is val:
            print('DEBUG:{} -> {}'.format(name, val), file=sys.stderr)
            return None

def solve():
    inf = float('inf')
    n = int(input())
    a = []

    for i in range(n):
        line = [int(i) for i in input().split()]
        line = [i if i != -1 else inf for i in line]
        a.append(line)

    
    checked = [False] * n
    d = [inf] * n
    checked[0] = True
    ans = 0
    nxt = 0

    for i in range(n - 1):
        for j in range(n):
            if a[nxt][j] < d[j]:
                d[j] = a[nxt][j]

        min_w = inf
        min_n = 0

        for j in range(n):
            if not checked[j] and d[j] < min_w:
                min_n = j
                min_w = d[j]

        checked[min_n] = True
        nxt = min_n
        ans += min_w

    # debug(d, locals())
    print(ans)



if __name__ == '__main__':
    solve()

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#!/usr/bin/env python
from __future__ import division, print_function
from sys import stdin, maxint
 
 
def main():
    num = int(stdin.readline())
 
    M = []
    for _ in xrange(num):
        M.append([int(s) for s in stdin.readline().split()])
 
    g = set(xrange(1, num+1))
    index = g.pop()
    h = {index}
    weight = 0
 
    while g:
        minimum = maxint
        for j in h:
            mj = M[j-1]
            for i in g:
                if 0 <= mj[i-1] < minimum:
                    index = i
                    minimum = mj[i-1]
        h.add(index)
        g.remove(index)
        weight += minimum
 
    print(weight)

Python: def Serch():
    unit = [2001]
    for j in Tree:
        for i in range(1, n):
            if G[j][i] != -1 and i not in Tree:
                unit.append(G[j][i])
    for j in Tree:
        for i in range(1, n):
            if G[j][i] == min(unit) and i not in Tree:
                ans.append(int(G[j][i]))
                Tree.append(i)
                Serch()
                break


n = int(input())
G = []
for i in range(n):
    G.append(input().split())
    for j in range(len(G[i])):
        G[i][j] = int(G[i][j])

ans = []
Tree = [0]
Serch()
print(sum(ans))

Python: def memoize(f):  
    cache = {}  
    def helper(x):  
        if x not in cache:              
            cache[x] = f(x)  
        return cache[x]  
    return helper 

def split_apex(a):
    if len(a) == 2:
        yield (a[0],), (a[1],)
    else:
        for i in range(0, len(a)):
            yield (a[i],), a[:i] + a[i + 1:]

@memoize
def wait(a):
    global g
    if len(a) == 1:
        return 0
    return min(calc_wait(apex, apices) for apex, apices in split_apex(a))

def calc_wait(apex, apices):
    global g
    w = [g[apex[0]][i] for i in apices if g[apex[0]][i] != -1]
    return  wait(apex) + wait(apices) + (min(w) if len(w) else 200000)

n = int(input())
g = [None] + [[None] + list(map(int, input().split())) for _ in range(n)]

a = tuple(i + 1 for i in range(n))
print(wait(a))

Python: def prim(cost):
    sumcost = 0
    V = len(cost)
    mincost = [float('inf')] * V
    used = [False] * V
    mincost[0] = 0
    while True:
        j = -1
        for i in range(V):
            if not used[i] and (j == -1 or mincost[i] < mincost[j]):
                j = i
        if j == -1:
            break
        used[j] = True
        sumcost = sumcost + mincost[j]
        for i in range(V):
            if cost[i][j] == -1:
                continue
            mincost[i] = min(mincost[i], cost[j][i])
    return sumcost
 
n = int(raw_input())
A = [0] * n
for i in range(n):
    A[i] = map(int, raw_input().split())
 
result = prim(A)
print(result)

Python: n = int(input())
#簡単のため、プリム法で回答する
data = []
for _ in range(n):
    line = list(map(int,input()[1:].split(' ')))
    for i in range(len(line)):
        if line[i] == -1:
            line[i] = 2001
    data.append(line)

been = [0]
unBeen = []
count = 0
while True:
    minIndex = [0,0]
    min = 2001
    for ele in been:
        for i in range(len(data[ele])):
            if min > data[ele][i] and not i in been:
                min = data[ele][i]
                minIndex = [ele,i]

    count += data[minIndex[0]][minIndex[1]]
    data[minIndex[0]][minIndex[1]] = 2001
    data[minIndex[1]][minIndex[0]] = 2001
    been.append(minIndex[1])
    if len(been) == n:
        break

print(count)

Python: n=int(input())
M=[list(map(int,input().split()))for _ in[0]*n]
d=[0]+[1e4]*n
b=[1]*n
a=0
while 1:
 u=-1
 for i in range(n):
  if b[i]and(u<0 or d[i]<d[u]):u=i
 if u<0:break
 b[u]=0
 a+=d[u]
 for v in range(n):
  t=M[u][v]
  if t+1 and d[v]>t:d[v]=t
print(a)

Python: n = int(input())
M = [list(map(int, input().split())) for _ in range(n)]
INF = 100000000000
color = ['White']*n
d = [INF]*n
p = [-1]*n
d[0] = 0
sum = 0

while True:
    minct = INF
    u = -1
    for i in range(n):
        if color[i] != 'Black' and d[i] < minct:
            minct = d[i]
            u = i
    if minct == INF:
        break
    color[u] = 'Black'
    for j in range(n):
        if color[j] != 'Black' and M[u][j] != -1:
            if M[u][j] < d[j]:
                d[j] = M[u][j]
                p[j] = u
                color[j] = 'Gray'
for k in range(n):
    if p[k] != -1:
        sum += M[k][p[k]]
print(sum)