Go: package main

import (
	"bufio"
	"container/heap"
	"fmt"
	"os"
	"strconv"
)

type Node struct {
	id     int
	weight int
}

func init() {
	sc.Split(bufio.ScanWords)
}

type NodeHeap []Node

func (h NodeHeap) Len() int           { return len(h) }
func (h NodeHeap) Less(i, j int) bool { return h[i].weight < h[j].weight }
func (h NodeHeap) Swap(i, j int)      { h[i], h[j] = h[j], h[i] }

func (h *NodeHeap) Push(x interface{}) {
	*h = append(*h, x.(Node))
}

func (h *NodeHeap) Pop() interface{} {
	old := *h
	n := len(old)
	x := old[n-1]
	*h = old[0 : n-1]
	return x
}

var sc = bufio.NewScanner(os.Stdin)

func scanInt() int {
	num, _ := strconv.Atoi(scanString())
	return num
}

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

func init() {
	sc.Split(bufio.ScanWords)
}

func main() {
	n := scanInt()

	list := make([][]int, n)
	seen := make([]bool, n)
	for i := range list {
		list[i] = make([]int, n)
		for j := range list[i] {
			list[i][j] = scanInt()
		}
	}

	start := Node{id: 0, weight: 0}
	h := &NodeHeap{start}
	heap.Init(h)

	sum := 0
	for h.Len() > 0 {
		node := heap.Pop(h).(Node)
		if seen[node.id] {
			continue
		}
		seen[node.id] = true
		sum += node.weight

		for i, w := range list[node.id] {
			if w < 0 {
				continue
			}
			heap.Push(h, Node{id: i, weight: w})
		}
	}

	fmt.Println(sum)
}

Python: # coding: utf-8

class UnionFind:
    def __init__(self,N):
        self.par = [i for i in range(N)]
        self.rank = [1]*N
        
    def find(self, x):
        if self.par[x] == x:
            return x
        else:
            self.par[x] = self.find(self.par[x])
            return self.par[x]
    
    def unite(self, x, y):
        x = self.find(x)
        y = self.find(y)
        if x == y:
            return
        
        if self.rank[x] < self.rank[y]:
            self.par[x] = y
        else:
            self.par[y] = x
            if self.rank[x] == self.rank[y]:
                self.rank[x] += 1

    def same(self, x, y):
        return self.find(x) == self.find(y)
        
class Edge:
    def __init__(self, u, v, cost):
        self.u = u
        self.v = v
        self.cost = cost

def kruskal():
    es.sort(key=lambda x: x.cost)
    uf = UnionFind(V)
    res = 0
    for i in range(E):
        if not uf.same(es[i].u, es[i].v):
            uf.unite(es[i].u, es[i].v)
            res += es[i].cost
            
    return res

V = int(input().rstrip())
E = 0
es = []
for i in range(V):
    line = list(map(int, input().rstrip().split()))
    for j in range(V):
        if line[j] != -1:
            es.append(Edge(i,j,line[j]))
            E += 1

ans = kruskal()
print(ans)

Python: INF = 9999


def prim(M):
    n = len(M)
    color = [0] * n
    d = [INF] * n
    d[0] = 0

    while True:
        minv = INF
        u = -1
        for i in range(n):
            # Black:2
            if minv > d[i] and color[i] != 2:
                u = i
                minv = d[i]
        if u == -1: break
        color[u] = 2

        for v in range(n):
            if color[v] != 2 and M[u][v] != INF:
                if d[v] > M[u][v]:
                    d[v] = M[u][v]
    return sum(d)


if __name__ == '__main__':
    n = int(input())
    A = []
    for i in range(n):
        for j in range(n):
            src = input()
            dst = src.replace('-1', 'INF')
            ai = list(map(int, dst.split()))
            A.append(ai)
    print(prim(A))

Python: N = int(input())
color = ["w" for _ in range(N)]
d = [float("inf") for _ in range(N)]
p = [-1 for _ in range(N)]

# Make M
M = [list(map(int, input().split())) for _ in range(N)]

d[0] = 0
while True:
    mincost = float("inf")
    for i in range(N):
        if color[i] != "b" and d[i] < mincost:
            mincost = d[i]
            u = i
    
    if mincost == float("inf"):
        break
    color[u] = "b"

    for v in range(N):
        if color[v] != "b" and M[u][v] != -1:
            if d[v] > M[u][v]:
                d[v] = M[u][v]
                p[v] = u

s = 0 
for i in range(1, N):
    s += M[i][p[i]]
print(s)

Python: from __future__ import division, print_function
from sys import stdin, maxint
 
 
def main():
    num = int(stdin.readline())
 
    y = []
    for _ in xrange(num):
        it = iter(int(s) for s in stdin.readline().split()[1:])
        y.append([(next(it), next(it)) for _ in xrange(next(it))])
    weight = [maxint] * num
    weight[0] = 0
    t = set(xrange(1, num))
    index = 0
 
    while t:
        for v, cost in y[index]:
            if v not in t:
                continue
            weight[v] = min(weight[v], cost + weight[index])
        index = min(t, key=lambda i: weight[i])
        t.remove(index)
    for i, d in enumerate(weight):
        print(i, d)
 
 
main()

Python: from __future__ import division, print_function
from sys import stdin, maxint
 
 
def main():
    num = int(stdin.readline())
 
    y = []
    for _ in xrange(num):
        it = iter(int(s) for s in stdin.readline().split()[1:])
        y.append([(next(it), next(it)) for _ in xrange(next(it))])
 
    weight = [maxint] * num
    weight[0] = 0
    t = set(xrange(1, num))
    index = 0
 
    while t:
        for v, cost in y[index]:
            if v not in t:
                continue
            weight[v] = min(weight[v], cost + weight[index])
 
        index = min(t, key=lambda i: weight[i])
        t.remove(index)
 
    for i, d in enumerate(weight):
        print(i, d)
 
 
main()

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()

if __name__ == "__main__":
    main()

Python: import heapq

n = int(input())
edges = [set((w, j) for j, w in enumerate(map(int, input().split())) if w > -1) for _ in range(n)]


def get_minimum():
    global n, edges
    visited = [False] * n
    visited[0] = True
    queue = list(edges[0])
    heapq.heapify(queue)
    total_cost = 0
    while queue:
        cost, vertex = heapq.heappop(queue)
        if visited[vertex]:
            continue
        visited[vertex] = True
        total_cost += cost
        if sum(visited) == n:
            return total_cost
        queue.extend(edges[vertex])
        heapq.heapify(queue)


print(get_minimum())

Python: 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)
    
    

n= int(input())
a=[]
P=[i for i in range(n)]

for i in range(n):
    temp= list(map(int,input().split()))
    for j in range(i,n):
        if temp[j] != -1:
            a.append([temp[j], i, j])
a.sort()
ans=0
for i in a:
    if not(is_same_set(P[i[1]],P[i[2]])):
        unite(i[1],i[2])
        ans+= i[0]
print(ans)

Python: n = int(input())
edgeList = []
rootList = [-1 for i in range(n)]

def getRoot(x):
    r = rootList[x]
    if r < 0:
        rootList[x] = x
    elif r != x:
        rootList[x] = getRoot(r)
    return rootList[x]
        
for i in range(n):
    a = list(map(int, input().split()))
    for j in range(i):
        if a[j] != -1:
            edgeList.append([a[j], getRoot(i), getRoot(j)])
sumLength = 0
edgeList.sort(key=lambda x: x[0])
for e in edgeList:
    x = getRoot(e[1])
    y = getRoot(e[2])
    if x != y:
        sumLength += e[0]
        rootList[x] = rootList[y] = min(x, y)
print(sumLength)