Go: package main

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

// I/O
type Scanner struct {
	sc *bufio.Scanner
}

func NewScanner() *Scanner {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Buffer(make([]byte, 1024), int(1e+9))
	return &Scanner{sc}
}

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

func (s *Scanner) nextInt() int {
	i, e := strconv.Atoi(s.nextStr())
	if e != nil {
		panic(e)
	}
	return i
}

func (s *Scanner) nextFloat() float64 {
	f, e := strconv.ParseFloat(s.nextStr(), 64)
	if e != nil {
		panic(e)
	}
	return f
}

func (s *Scanner) nextRuneSlice() []rune {
	return []rune(s.nextStr())
}

func (s *Scanner) nextIntSlice(n int) []int {
	res := make([]int, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextInt()
	}
	return res
}

func (s *Scanner) nextFloatSlice(n int) []float64 {
	res := make([]float64, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextFloat()
	}
	return res
}

// Arithmetic
func max(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m < i {
			m = i
		}
	}
	return m
}

func min(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m > i {
			m = i
		}
	}
	return m
}

func abs(x int) int {
	if x > 0 {
		return x
	}
	return -x
}

func pow(x, y int) int {
	res := 1
	for i := 0; i < y; i++ {
		res *= x
	}
	return res
}

func ceil(a, b int) int {
	if a%b == 0 {
		return a / b
	} else {
		return a/b + 1
	}
}

// Sort
type RuneSlice []rune

func (a RuneSlice) Len() int           { return len(a) }
func (a RuneSlice) Less(i, j int) bool { return a[i] < a[j] }
func (a RuneSlice) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

// Main
type Node struct {
	cost int
	done bool
}

type Edge struct {
	to, cost int
}

const INF = 1 << 60

func main() {
	sc := NewScanner()
	wtr := bufio.NewWriter(os.Stdout)
	N := sc.nextInt()
	nodes := make([]Node, N)
	for i := 0; i < N; i++ {
		nodes[i].cost = INF
	}
	E := make([][]Edge, N)
	for i := 0; i < N; i++ {
		id, k := sc.nextInt(), sc.nextInt()
		for j := 0; j < k; j++ {
			to, cost := sc.nextInt(), sc.nextInt()
			E[id] = append(E[id], Edge{to, cost})
		}
	}
	nodes[0].cost = 0
	for {
		cur := 0
		minCost := INF
		for i := 0; i < N; i++ {
			n := nodes[i]
			if !n.done && n.cost < minCost {
				cur = i
				minCost = n.cost
			}
		}
		if minCost == INF {
			break
		}
		nodes[cur].done = true
		for i := 0; i < len(E[cur]); i++ {
			to, cost := E[cur][i].to, E[cur][i].cost+nodes[cur].cost
			if !nodes[to].done && cost < nodes[to].cost {
				nodes[to].cost = cost
			}
		}
	}

	for i := 0; i < N; i++ {
		fmt.Fprintln(wtr, i, nodes[i].cost)
	}
	wtr.Flush()
}

Python: # -*- coding: utf-8 -*-

N = int(input())
INF = float("inf")
adj = [[INF]*N for _ in range(N)]

for n in range(N):
    inp = tuple(map(int, input().split()))
    assert n == inp[0]
    for i in range(inp[1]):
        adj[inp[0]][inp[2*i+2]] = inp[2*i+3]

not_MST = list(range(1, N))
MST = [0]
costs = {n:INF for n in range(N)}
costs[0] = 0

for n in range(1, N):
    if adj[0][n] < INF:
        costs[n] = adj[0][n]

m = 0

while len(not_MST):
    tmp_min = INF
    tmp_idx = -1
    
    for n in not_MST:
        if costs[m] + adj[m][n] < costs[n]:
            costs[n] = costs[m] + adj[m][n]
    
    for m in not_MST:
        if costs[m] < tmp_min:
            tmp_min = costs[m]
            tmp_idx = m
    
    MST.append(tmp_idx)
    not_MST.remove(tmp_idx)
    m = tmp_idx

for n in range(N):
    print("{} {}".format(n, costs[n]))

Python: n = int(input())

adj = [[100001 for j in range(n)] for i in range(n)]

for u in range(n):
    x = list(map(int, input().split()))
    for v, c in zip(x[2::2], x[3::2]):
        adj[u][v] = c

unvisited = [v for v in range(n)]

distance = [9900001] * n


def dijkstra(s):
    distance[s] = 0

    while True:
        mincost = 9900001
        for i in unvisited:
            if distance[i] < mincost:
                mincost = distance[i]
                u = i

        if mincost == 9900001:
            break

        unvisited.remove(u)

        for v in unvisited:
            weight_uv = adj[u][v]
            if weight_uv != 100001:
                t_d = distance[u] + weight_uv
                if t_d < distance[v]:
                    distance[v] = t_d



dijkstra(0)

for v, d in enumerate(distance):
    print(v, d)

Python: n = int(input())
edgeList = []

for i in range(n):
    a = list(map(int, input().split()))
    for j in range(a[1]):
        edgeList.append([a[2*j+3], i, a[2*j+2]])

rootList = [-1 for i in range(n)]
parent = [0 for i in range(n)]
lenList = [0 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]


edgeList.sort(key=lambda x: x[0])
flag = True
while flag:
    flag = False
    for e in edgeList:
        if e[2] == 0:
            continue
        x = getRoot(e[1])
        y = getRoot(e[2])
        if x == 0 != y:
            parent[e[2]] = e[1]
            lenList[e[2]] += lenList[e[1]] + e[0]
            rootList[y] = 0
            flag = True
            break

for i, j in zip(range(n), lenList):
    print(i, j)

Python: from sys import stdin

INFTY = 1 << 21
WHITE = 0
GRAY = 1
BLACK = 2

n = int(stdin.readline())
M = [[INFTY for i in range(n)] for j in range(n)]

for u in range(n):
    U = list(map(int, stdin.readline().split()[2:]))
    for j in range(0, len(U), 2):
        M[u][U[j]] = U[j+1]

d = [INFTY for i in range(n)]
color = [WHITE for i in range(n)]

def dijkstra():
    global n
    d[0] = 0
    color[0] = GRAY
    while(1):
        minv = INFTY
        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] != INFTY):
                if(d[v] > d[u] + M[u][v]):
                    d[v] = d[u] + M[u][v]
                    color[v] = GRAY
    for i in range(
n):
        print(i, (-1 if d[i] == INFTY else d[i]))
dijkstra()

Python: import heapq


class SSST:
    """Given weighted graph, find minimum spanning tree.

    >>> st = SSST([[(2, 3), (3, 1), (1, 2)], \
                   [(0, 2), (3, 4)], \
                   [(0, 3), (3, 1), (4, 1)], \
                   [(2, 1), (0, 1), (1, 4), (4, 3)], \
                   [(2, 1), (3, 3)]])
    >>> [st.weight(n) for n in range(5)]
    [0, 2, 2, 1, 3]
    """
    def __init__(self, graph):
        self.size = len(graph)
        self.tree = []
        self.weights = [0] * self.size
        self._search(graph)

    def weight(self, n):
        return self.weights[n]

    def _search(self, graph):
        visited = [0]

        while len(visited) < self.size:
            h = []
            for node in visited:
                for i, w in graph[node]:
                    if i not in visited:
                        heapq.heappush(h, (w+self.weights[node], node, i))

            weight, src, dst = heapq.heappop(h)
            visited.append(dst)
            self.weights[dst] = weight
            self.tree.append((src, dst))


def run():
    n = int(input())

    nodes = [None] * n
    for _ in range(n):
        id_, deg, *edges = [int(i) for i in input().split()]
        nodes[id_] = []
        for _ in range(deg):
            tgt, wgt, *edges = edges
            nodes[id_].append((tgt, wgt))

    st = SSST(nodes)
    for node in range(n):
        print('{} {}'.format(node, st.weight(node)))


if __name__ == '__main__':
    run()