Go: package main

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

const (
	MAX_N      = 10000
	MAX_WEIGHT = 100000
)

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, err := createAdjacentMatrix(n, sc)
	if err != nil {
		panic(err)
	}

	sssp([]int{1}, shortestList, adjacentMatrix)
	for _, v := range shortestList {
		fmt.Printf("%d %d\n", v.getEnd()-1, v.shortest)
	}
}

func (si ShortestInfo) getEnd() int {
	if len(si.edges) == 0 {
		return 1
	} else {
		return si.edges[len(si.edges)-1].end
	}
}

func createAdjacentMatrix(n int, sc *bufio.Scanner) ([][]int, error) {
	adjacentMatrix := make([][]int, n)
	for i := 0; i < n; i++ {
		id, err := nextInt(sc)
		if err != nil {
			return nil, err
		}
		adjacentMatrix[id] = make([]int, n)
		for j := 0; j < n; j++ {
			adjacentMatrix[id][j] = -1
		}
		vertexNum, err := nextInt(sc)
		if err != nil {
			return nil, err
		}
		for j := 0; j < vertexNum; j++ {
			v, err := nextInt(sc)
			if err != nil {
				return nil, err
			}
			c, err := nextInt(sc)
			if err != nil {
				return nil, err
			}
			adjacentMatrix[id][v] = c
		}
	}
	return adjacentMatrix, nil
}

func sssp(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]
			if currentShortest.shortest+adj.weight < getShortest(adj.end, shortestList).shortest {
				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: # -*- coding: utf-8 -*-
"""
http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=ALDS1_12_C

???????§????????????????II
"""
from enum import Enum
from heapq import heappush, heappop, heapify
import itertools


class Priority_queue():
    # https://docs.python.jp/3/library/heapq.html
    def __init__(self):
        self.pq = []                         # list of entries arranged in a heap
        self.entry_finder = {}               # mapping of tasks to entries
        self.REMOVED = '<removed-task>'      # placeholder for a removed task
        self.counter = itertools.count()     # unique sequence count

    def add_task(self, task, priority=0):
        'Add a new task or update the priority of an existing task'
        if task in self.entry_finder:
            self.remove_task(task)
        count = next(self.counter)
        entry = [priority, count, task]
        self.entry_finder[task] = entry
        heappush(self.pq, entry)

    def remove_task(self, task):
        'Mark an existing task as REMOVED.  Raise KeyError if not found.'
        entry = self.entry_finder.pop(task)
        entry[-1] = self.REMOVED

    def pop_task(self):
        'Remove and return the lowest priority task. Raise KeyError if empty.'
        while self.pq:
            priority, count, task = heappop(self.pq)
            if task is not self.REMOVED:
                del self.entry_finder[task]
                return task
        raise KeyError('pop from an empty priority queue')

    def top_task(self):
        return self.pq[0][-1]

    def get_length(self):
        return len(self.pq)

    def is_empty(self):
        return self.get_length()==0


class Sssp(object):
    """ single source shortest path """
    INFINITY = 999999999
    class Status(Enum):
        """ ?????????????¨??????¶??? """
        white = 1  # ????¨????
        gray = 2  # ?¨???????
        black = 3  #?¨???????

    def __init__(self, data):
        num_of_nodes = len(data)
        self.color = [Sssp.Status.white] * num_of_nodes  # ????????????????¨??????¶???
        self.d = [Sssp.INFINITY] * num_of_nodes  # ?§???????????????????
        self.p = [-1] * num_of_nodes  # ????????????????????????????¨?????????????????????????
        self.adj = [[] for _ in range(num_of_nodes)]
        self.make_adj(data)


    def make_adj(self, data):
        # ??£??\??????????????????
        for d in data:
            my_id = d[0]
            d = d[2:]
            while len(d) > 1:
                to_node, cost = d[0], d[1]
                self.adj[my_id].insert(0, (to_node, cost))
                d = d[2:]


    def dijkstra(self, start):
        self.d[start] = 0
        pq = Priority_queue()
        pq.add_task((0, 0), 0)

        while not pq.is_empty():
            cost, u = pq.pop_task()
            self.color[u] = Sssp.Status.black
            if self.d[u] < cost:
                continue

            for v, cost in self.adj[u]:
                if self.color[v] == Sssp.Status.black:
                    continue
                if self.d[v] > self.d[u] + cost:
                    self.d[v] = self.d[u] + cost
                    pq.add_task((self.d[v], v), self.d[v])
                    self.color[v] = Sssp.Status.gray


if __name__ == '__main__':
    # ??????????????\???
    num = int(input())
    data = []
    for i in range(num):
        data.append(list(map(int, input().split(' '))))

    # ???????????¢?´¢
    s = Sssp(data)
    s.dijkstra(0)

    # ???????????¨???
    for i in range(num):
        print('{0} {1}'.format(i, s.d[i]))