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: 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
    d[0] = 0
    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()

Python: def prim():
    global M
    global n
    global INF
    color = ['w' for i in range(n)]
    d = [INF for i in range(n)]
    d[0] = 0
    p = [-1 for i in range(n)]

    while True:
        mincost = INF
        u = -1
        for i in range(n):
            if color[i] != 'b' and d[i] < mincost:
                mincost = d[i]
                u = i
        if u == -1:
            break
        color[u] = 'b'
        for v in range(n):
            if color[v] != 'b' and M[u][v] != INF:
                if M[u][v] < d[v]:
                    d[v] = M[u][v]
                    p[v] = u
                    color[v] = 'g'
    s = 0
    for i in range(n):
        if p[i] != -1:
            s += M[i][p[i]]
    return s


INF = 3000
n = int(input())

M = [[0 for j in range(n)] for i in range(n)]

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

Python: def prim():
    INFTY = float('inf')
    color = ['WHITE' for _ in range(n)]
    d = [INFTY for _ in range(n)]
    p = [None for _ in range(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

        color[u] = 'BLACK'

        for v in range(n):
            if color[v] != 'BLACK' and A[u][v] != -1:
                if A[u][v] < d[v]:
                    d[v] = A[u][v]
                    p[v] = u
                    color[v] = 'GRAY'
    return sum(d)

n = int(input())
A = []
for _ in range(n):
    l = list(map(int, input().split()))
    A.append(l)

print(prim())

Python: N = int(input())
M = [list(map(int, input().split())) for i in range(N)]
INF = 2001
MAX = 100
d = [INF for i in range(N)]
d[0] = 0
p = [MAX for i in range(N)]
p[0] = -1
mst = [False for i in range(N)]

while True:
  min_w = INF
  for i in range(N):
    if not mst[i] and d[i] < min_w:
      min_w = d[i]
      u = i
  if min_w == INF:
    break
  mst[u] = True
  for v in range(N):
    if not mst[v] and M[u][v] != -1:
      if M[u][v] < d[v]:
        d[v] = M[u][v]
        p[v] = u

print(sum(d))

Python: n = int(input())
adj = [[0 for i in range(n)] for j in range(n)]

for i in range(n):
    tmp = list(map(int, input().split()))
    u = tmp[0]
    u = u -1
    k = tmp[1]
    v = tmp[2:] -1
    for j in range(k):
        adj[u][v[j]] = 1
        
for i in range(n):
        print(" ".join(list(map(str, adj[i]))))

Python: def main():

    N = 100

    n = int(input())
    adj = [[0 for i in range(n)] for j in range(n)]

    for i in range(n):
        tmp = list(map(int, input().split()))
        u = tmp[0]
        u = u -1
        k = tmp[1]
        v = tmp[2:]
        for j in range(k):
            adj[u][v[j]-1] = 1

    for i in range(n):
        for j in range(n):
            print(adj[i][j], end=" ")
        print()
    return 0

if __name__ == "__main__":
    return main()