Go: package main

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

var scanner = bufio.NewScanner(os.Stdin)

func nextString() string {
	scanner.Scan()
	return scanner.Text()
}

func nextInt() int {
	n, err := strconv.Atoi(nextString())
	if err != nil {
		fmt.Printf("strconv.Atoi failed: %v\n", err)
	}
	return n
}

var infty = 1000000000

type DirectedGraphNodeID int

type DirectedGraphNode struct {
	key         DirectedGraphNodeID
	adjacents   []*DirectedGraphNode
	costs       []int
	distance    int
	predecessor *DirectedGraphNode
}

func newDirectedGraph(nNodes int) *DirectedGraph {
	graph := DirectedGraph{}
	graph.nodes = make([]*DirectedGraphNode, nNodes)
	for i := 0; i < nNodes; i++ {
		node := DirectedGraphNode{}
		node.key = DirectedGraphNodeID(i)
		node.distance = infty
		graph.nodes[i] = &node
	}
	return &graph
}

type DirectedGraph struct {
	nodes []*DirectedGraphNode
}

func (g *DirectedGraph) setAdjacency(i, j DirectedGraphNodeID, cost int) {
	g.nodes[i].adjacents = append(g.nodes[i].adjacents, g.nodes[j])
	g.nodes[i].costs = append(g.nodes[i].costs, cost)
}

func (g *DirectedGraph) print() {
	for i := 0; i < len(g.nodes); i++ {
		node := g.nodes[i]
		key := node.key
		strings := []string{strconv.Itoa(int(key)), strconv.Itoa(node.distance)}
		for j := 0; j < len(node.adjacents); j++ {
			nodeJ := fmt.Sprintf("(%v, %v)", node.adjacents[j].key, node.costs[j])
			strings = append(strings, nodeJ)
		}
		fmt.Printf("%v\n", strings)
	}
}

func (g *DirectedGraph) relaxEdge(l, r *DirectedGraphNode, w int) {
	if r.distance > l.distance+w {
		// fmt.Printf("%v -> %v, %v\n", l.key, r.key, l.distance+w)
		r.distance = l.distance + w
		r.predecessor = l
	}
}

func main() {
	scanner.Split(bufio.ScanWords)

	nNodes := nextInt()
	graph := newDirectedGraph(nNodes)

	for i := 0; i < nNodes; i++ {
		iNode := DirectedGraphNodeID(nextInt())
		nAdjacent := nextInt()
		for j := 0; j < nAdjacent; j++ {
			jNode := DirectedGraphNodeID(nextInt())
			cost := nextInt()
			graph.setAdjacency(iNode, jNode, cost)
		}
	}

	graph.nodes[0].distance = 0
	for iNode := 0; iNode < nNodes; iNode++ {
		for iLeft := 0; iLeft < len(graph.nodes); iLeft++ {
			nodeLeft := graph.nodes[iLeft]
			for iRight := 0; iRight < len(nodeLeft.adjacents); iRight++ {
				nodeRight := nodeLeft.adjacents[iRight]
				cost := nodeLeft.costs[iRight]
				graph.relaxEdge(nodeLeft, nodeRight, cost)
			}
		}
	}

	// graph.print()

	for iNode := 0; iNode < len(graph.nodes); iNode++ {
		node := graph.nodes[iNode]
		fmt.Println(node.key, node.distance)
	}
}

Python: import heapq


class Graph(object):

    class Node:
        def __init__(self, dist: int, number: int):
            self.dist = dist
            self.number = number

        def __lt__(self, other):
            return self.dist < other.dist \
                   or (self.dist == other.dist
                       and self.number < other.number)

        def __le__(self, other):
            return self.dist <= other.dist

        def __gt__(self, other):
            return other <= self

        def __ge__(self, other):
            return other < self

        def __str__(self):
            return "Node: (" + str(self.number) + ", " \
                   + str(self.dist) + ")"

    class Edge:
        def __init__(self, to: int, cost: int):
            self.to = to
            self.cost = cost

        def __str__(self):
            return "Edge: (" + str(self.to) + ", " \
                   + str(self.cost) + ")"

    INF = 10e10

    def __init__(self, node_n: int, start: int):
        self.node_n = node_n
        self.start = start
        self.edges = [{} for _ in range(self.node_n)]
        self.dist = [self.INF for _ in range(self.node_n)]

    def set_edge(self, from_pos: int, to_pos: int, cost: int, reversible: bool) -> None:
        self.edges[from_pos][to_pos] = (self.Edge(to_pos, cost))
        if reversible:
            self.edges[to_pos][from_pos] = (self.Edge(from_pos, cost))

    def solve(self) -> list:
        raise NotImplementedError


class Dijkstra(Graph):
    hq = []
    prev: list

    def __init__(self, node_n: int, start: int):
        super(Dijkstra, self).__init__(node_n, start)
        self.dist[self.start] = 0
        self.prev = [None for _ in range(node_n)]

    def solve(self) -> list:
        heapq.heappush(self.hq, self.Node(0, self.start))

        while len(self.hq) != 0:
            node = heapq.heappop(self.hq)
            if node.dist > self.dist[node.number]:
                continue

            for edge in self.edges[node.number].values():
                alt = self.dist[node.number] + edge.cost
                if self.dist[edge.to] > alt:
                    self.dist[edge.to] = alt
                    self.prev[edge.to] = node.number
                    heapq.heappush(self.hq, self.Node(self.dist[edge.to], edge.to))

        return self.dist


if __name__ == '__main__':
    n = int(input())
    graph = Dijkstra(n, 0)

    for _ in range(n):
        buff = list(map(int, input().split()))
        u = buff[0]
        k = buff[1]
        for i in range(k):
            graph.set_edge(u,
                           buff[2 + i * 2],
                           buff[3 + i * 2],
                           False)
    dist = graph.solve()
    for i, d in enumerate(dist):
        print(i, d)

Python: inf = float("inf")
n = int(input())
M = [[inf for i in range(n)] for i in range(n)]
for i in range(n):
    L = list(map(int, input().split()))
    for j in range(L[1]):
        M[L[0]][L[2 * j + 2]] = L[2 * j + 3]


def dijkstra(s):
    color = [0] * n
    d = [inf] * n
    d[s] = 0

    while True:
        mincost = inf
        for i in range(n):
            if color[i] !=1 and d[i] < mincost:
                mincost = d[i]
                u = i
        if mincost == inf: break
        color[u] = 1
        for v in range(n):
            if color[v] != 1 and M[u][v] != inf:
                if d[u] + M[u][v] < d[v]:
                    d[v] = d[u] + M[u][v]

    return d

d = dijkstra(0)
for i,v in enumerate(d):
 print("{} {}".format(i,v))

Python: class Graph:
    def __init__(self,V,E):
        self.V = V
        self.E = E

    def WF(self,st):
        N,INF = len(self.V),10**7+1
        dp = [INF for _ in range(N)]
        #dp[i]:頂点stから頂点iへの最小距離
        dp[st] = 0
        update = True
        while update:
            update = False
            for i in range(N):
                for j in range(N):
                    if (j,i) in self.E:
                        if dp[i] > dp[j] + self.E[(j,i)]:
                            dp[i] = dp[j] + self.E[(j,i)]
                            update = True
        return dp

def main():
    n = int(input())
    I = [list(map(int,input().split())) for _ in range(n)]
    V = set([i for i in range(n)])
    E = {}
    for i in range(n):
        for j in range(I[i][1]):
            E[(I[i][0],I[i][j*2+2])] = I[i][j*2+3]
    G = Graph(V,E)
    sp = G.WF(0)
    for i in range(n):
        print(i,sp[i])

if __name__ == "__main__":
    main()