Go: package main

import (
	"strconv"
	"fmt"
	"bufio"
	"os"
)
const INF = 1 << 21
var scanner = bufio.NewScanner(os.Stdin)

func nextInt() int {
	scanner.Scan()
	i, e := strconv.Atoi(scanner.Text())
	if e != nil {
		panic(e)
	}
	return i
}


func main() {
	scanner.Split(bufio.ScanWords)
	n := nextInt()
	adj := make([][]int, n)
	for i := range adj {
		adj[i] = make([]int, n)
	}

	for i := 0;i < n; i++ {
		u := nextInt()
		k := nextInt()
		for j := 0; j < k; j++ {
			v := nextInt()
			c := nextInt()
			adj[u][v] = c
		}
	}

	// for i := range adj {
	// 	fmt.Println(adj[i])
	// }

	dist := make([]int, n)
	prev := make([]int, n)
	visited := make([]bool, n)
	dijkstra := func(start int, size int) {
		for i := 0; i < size; i++ {
			dist[i] = INF
			prev[i] = -1
			visited[i] = false
		}
		dist[start] = 0
		for {
			u := -1
			tmp_min := INF
			for i := 0; i < size; i++ {
				if visited[i] == false && dist[i] < tmp_min {
					tmp_min = dist[i]
					u = i
				}
			}
			if u == -1 {
				break
			}
			visited[u] = true
			for i := 0; i < size; i++ {
				if adj[u][i] > 0 {
					w := adj[u][i]
					newlen := dist[u] + w
					if newlen < dist[i] {
						dist[i] = newlen
						prev[i] = u
					}
				}
			}
		}
	}
	dijkstra(0, n)
	for i, cost := range dist {
		fmt.Printf("%d %d\n", i, cost)
	}
}

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()

Python: # -*- coding: utf-8 -*-
"""
Created on Tue May 21 23:08:18 2019

@author: Yamazaki Kenichi
"""

n = int(input())
A = [list(map(int,input().split())) for i in range(n)]
INFTY = 10**6
M = [[INFTY for i in range(n)] for i in range(n)]
for a in A:
    u, k = a[0], a[1]
    for i in range(k):
        M[u][a[i*2+2]] = a[i*2+3]

class Dijkstra(object):
    
    def __init__(self, size, INFTY=10**6):
        self.color = [-1 for i in range(size)]
        self.d = [INFTY for i in range(size)]
        self.p = [-1 for i in range(size)]
        self.d[0] = 0 
        self.p[0] = -1
    
    def add(self, M, INFTY=10**6):
        while True:
            mincost = INFTY
            for i in range(len(M)):
                if self.color[i] != 1 and self.d[i] < mincost:
                    mincost = self.d[i]
                    u = i
            if mincost == INFTY:
                break
            self.color[u] = 1            
            for v in range(len(M)):
                if self.color[v] != 1 and M[u][v] != INFTY:
                    if self.d[v] > self.d[u] + M[u][v]:
                        self.d[v] = self.d[u] + M[u][v]
                        self.p[v] = u
                        self.color[v] = 0
        return self.d

dij = Dijkstra(n)
ans = dij.add(M)
for i in range(n):
    print(i,ans[i])

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

import sys

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_list[0] = 0

    while True:
        min_cost = D_MAX
        current_vertex = None
        for i in range(vertices_num):
            if color[i] is not BLACK and path_list[i] < min_cost:
                min_cost = path_list[i]
                current_vertex = i

        if min_cost == D_MAX:
            break

        color[current_vertex] = BLACK

        for v in range(vertices_num):
            current_v_weight = adj_matrix[current_vertex].get(str(v), -1)
            if current_v_weight < 0:
                continue
            elif color[v] is not BLACK:
                if path_list[current_vertex] + current_v_weight < path_list[v]:
                    path_list[v] = path_list[current_vertex] + current_v_weight
                    parent_list[v] = current_vertex
                    color[v] = 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 = [{} for _ in range(vertices_num)]
    adj_matrix = generate_adj_matrix(init_vertices_table)
    ans = dijkstra_path()
    for j in range(vertices_num):
        print(j, ans[j])