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())
}

Python: WHITE = 0
GRAY = 1
BLACK = 2

INF = 1.0e+6

def prim(M):
    n = len(M)
    color = [WHITE] * n
    d = [INF] * n
    p = [-1] * n

    d[0] = 0

    while True:
        minv = INF
        u = -1
        for i in range(n):
            if minv > d[i] and color[i] != BLACK:
                u = i
                minv = d[i]

        if u == -1:
            break

        color[u] = BLACK
        for v in range(n):
            if color[v] != BLACK and M[u][v] != INF:
                if d[v] > M[u][v]:
                    d[v] = M[u][v]
                    p[v] = u
                    color[v] = GRAY

    sum = 0
    for i in range(n):
        if p[i] != -1:
            sum += M[i][p[i]]

    return sum


if __name__ == "__main__":
    n = int(input())

    M = [] * n

    for i in range(n):
        M.append(list(map(int, input().split())))
        M[i] = [INF if j == -1 else j for j in M[i]]

    print(prim(M))

Python: n = int(input())

INF = 2147483647
G = [[INF for j in range(n)] for i in range(n+1)]
check = [0 for i in range(n)]


def prim():
    d = [INF for i in range(n)]
    p = [-1 for i in range(n)]
    d[0] = 0
    cost = 0

    while True:
        min_cost = INF
        for i in range(n):
            if check[i] != 2 and d[i] < min_cost:
                min_cost = d[i]
                u = i

        if min_cost == INF:
            break

        cost += d[u]
        check[u] = 2

        for v in range(n):
            if check[v] != 2 and G[u][v] != INF:
                if G[u][v] < d[v]:
                    d[v] = G[u][v]
                    p[v] = u
                    check[v] = 1

    return cost


def main():
    for i in range(n):
        data = list(map(int, input().split()))
        for j in range(n):
            if data[j] != -1:
                G[i][j] = data[j]

    print(prim())


if __name__ == '__main__':
    main()

Python: n = int(input())
A = [[int(i) for i in input().strip().split(" ")] for j in range(n)]

dp1={}

for i in range(n):
    for j in range(n):
        if A[i][j] != -1 :
            dp1[(i,j)] = A[i][j]
key = []
value = []
for i,j in sorted(dp1.items(), key=lambda x:x[1]):
    key.append(i)
    value.append(j)

c_v = []
N = len(key)
len_c_v = 0
ans = 0
itr = 0
while itr != N:
    if len_c_v == n:
        break
    i = key[itr][0]
    j = key[itr][1]
    if (i in c_v) == False and (j in c_v) == False:
        c_v.append(i)
        c_v.append(j)
        ans += value[itr]
        len_c_v += 2
        itr += 1
    elif (i in c_v) == False:
        c_v.append(i)
        ans += value[itr]
        itr += 1
        len_c_v += 1
    elif (j in c_v) == False:
        c_v.append(j)
        ans += value[itr]
        itr += 1
        len_c_v += 1
    else:
        itr += 1


if len_c_v != n:
    print(-1)
else:
    print(str(ans))

Python: def Serch():
    unit = [2001]
    for j in Tree:
        for i in range(1, n):
            G[j][i] = int(G[j][i])
            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())

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

Python: # input
n = int(input())
A = []
for _ in range(n):
    A.append(list(map(int, input().split())))
    
# 変数定義
inf = 100 * 2000 + 1
M = A.copy()
M = [[a if a > -1 else inf for a in line] for line in M]
d = [inf] * n
V = set([i for i in range(n)])
T = set()

# 探索
start = 0
target = start
d[target] = 0
T.add(target)
while V != T:
    for i in (V - T):
        if M[target][i] < d[i]:
            d[i] = M[target][i]

    min_wheght = min([d[i] for i in (V - T)])
    min_path = [i for i in (V - T) if d[i] == min_wheght][0]
    target = min_path
    T.add(target)

# 出力
print(sum(d))

Python: n = int(input())
A = []
for ni in range(n):
    tmp = [int(i) for i in input().split()]
    A.append([[i, t] for i, t in enumerate(tmp) if t != -1])

INF = 2001
V = [i for i in range(n)]
T = [0]
ans = 0
while len(T) != n:
    w = [-1, INF]
    for t in T:
        for a in A[t]:
            if a[1] < w[1]:
                w = a
                p = t
    ans += w[1]
    T.append(w[0])
    for ni in range(n):
        for i in range(len(A[ni])):
            if w[0] == A[ni][i][0]:
                del A[ni][i]
                break
    for ni in range(n):
        for i in range(len(A[ni])):
            if A[ni][i][0] == p:
                del A[ni][i]
                break

print(ans)