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: def shortest_path(V,uvc,start=0):
    distances = [INF]*V
    distances[start] = 0
    parents = list(range(V))

    for _ in range(V):
        modified = False
        for src,dst,cost in uvc:
            if distances[dst] > distances[src] + cost:
                distances[dst] = distances[src] + cost
                parents[dst] = src
                modified = True
        if modified == False:
            return distances,parents
    return None,None
import sys
INF = float("inf")
N = int(sys.stdin.readline())
G = tuple(tuple(map(int,sys.stdin.readline().rstrip().split()))[2:] for _ in range(N))
uvc = []
for i in range(N):
    for j in range(0,len(G[i]),2):
        uvc.append([i,G[i][j],G[i][j+1]])  
a,_ = shortest_path(N,uvc,0)
for i,v in enumerate(a):
    print(i,v)

Python: def Single_Source_Shortest_Path(adj_mat, cost, parent):
    N = len(cost)
    color = ["W" for n in range(N)]
    parent[0] = -1
    cost[0] = 0

    while True:
        mincost = 1000000

        for i in range(N):
            if color[i] != "B" and cost[i] < mincost:
                u = i
                mincost = cost[u]

        if mincost == 1000000:
            break

        color[u] = "B"

        for v in range(N):
            if color[v] != "B" and adj_mat[u][v] >= 0:
                if cost[v] > cost[u] + adj_mat[u][v]:
                    cost[v] = cost[u] + adj_mat[u][v]
                    parent[v] = u
                    color[v] = "G"

def Main():
    N = int(input())
    cost = [1000000 for n in range(N)]
    color = ["W" for n in range(N)]
    adj_mat = [[ -1 for n in range(N)] for n in range(N)]
    parent = [-1 for n in range(N)]

    for n in range(N):
        u, K, *p = map(int, input().split())

        for k in range(K):
            v, c = p[2*k], p[2*k + 1]
            adj_mat[u][v] = c

    Single_Source_Shortest_Path(adj_mat, cost, parent)

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

Main()

Python: N = 100
WHITE = 0
GRAY = 1
BLACK = 2
INF = float('inf')
M = None
d = [INF for _ in range(N)]
p = [0 for _ in range(N)]
color = [WHITE for _ in range(N)]
n = 0


def main():
    global n, M

    n = int(input())
    M = [[INF for _ in range(n)] for _ in range(n)]

    for i in range(n):
        _, k, *v_s = map(int, input().split(' '))
        for j in range(k):
            c_i = 2*j + 1
            v = v_s[2*j]
            M[i][v] = v_s[c_i]

    dijkstra(0)

    for i in range(n):
        print('{} {}'.format(i, d[i]))


def dijkstra(s):
    d[s] = 0
    p[s] = -1

    while True:
        mincost = INF
        for i in range(n):
            if color[i] != BLACK and d[i] < mincost:
                mincost = d[i]
                u = i

        if mincost == INF:
            break

        color[u] = BLACK

        for v in range(n):
            if color[v] != BLACK and M[u][v] != INF:
                if d[u] + M[u][v] < d[v]:
                    d[v] = d[u] + M[u][v]
                    p[v] = u
                    color[v] = GRAY


if __name__ == '__main__':
    main()

Python: #!/usr/bin/env python
# -*- coding: utf-8 -*-

"""
input:
5
0 3 2 3 3 1 1 2
1 2 0 2 3 4
2 3 0 3 3 1 4 1
3 4 2 1 0 1 1 4 4 3
4 2 2 1 3 3

output:
0 0
1 2
2 2
3 1
4 3
"""

import sys
import heapq as hp

WHITE, GRAY, BLACK = 0, 1, 2
D_MAX = int(1e7 + 1)


def generate_adj_matrix(v_info):
    for v_detail in v_info:
        v_index = int(v_detail[0])
        v_adj_length = int(v_detail[1])
        v_adj_list = v_detail[2:]
        # assert len(v_adj_list) == v_adj_length * 2
        for j in range(0, v_adj_length * 2, 2):
            init_adj_matrix[v_index][v_adj_list[j]] = int(v_adj_list[j + 1])

    return init_adj_matrix


def dijkstra_path():
    # path search init
    start_vertex_index = 0
    path_list[start_vertex_index] = 0
    path_heap = []
    # heapq: compare by tuple[0]
    hp.heappush(path_heap, (path_list[start_vertex_index], start_vertex_index))
    while len(path_heap) >= 1:
        current_vertex = hp.heappop(path_heap)[1]

        color[current_vertex] = BLACK

        for adj_vertex in range(vertices_num):
            current_adj_weight = adj_matrix[current_vertex].get(str(adj_vertex), -1)
            if current_adj_weight < 0:
                continue
            elif color[adj_vertex] is not BLACK:
                # d[u] + w[u,v]
                alt_path = path_list[current_vertex] + current_adj_weight
                if alt_path < path_list[adj_vertex]:
                    # update path_list
                    path_list[adj_vertex] = alt_path
                    # update heap
                    hp.heappush(path_heap, (alt_path, adj_vertex))
                    parent_list[adj_vertex] = current_vertex
                    color[adj_vertex] = GRAY

    return path_list


if __name__ == '__main__':
    _input = sys.stdin.readlines()
    vertices_num = int(_input[0])
    init_vertices_table = list(map(lambda x: x.split(), _input[1:]))
    # assert len(init_vertices_table) == vertices_num

    parent_list, path_list = [-1] * vertices_num, [D_MAX] * vertices_num
    color = [WHITE] * vertices_num
    init_adj_matrix = tuple(dict() for _ in range(vertices_num))
    adj_matrix = generate_adj_matrix(init_vertices_table)
    ans = dijkstra_path()
    for i, v in enumerate(ans):
        print(i, v)