Go: package main

import (
	"bufio"
	"container/heap"
	"fmt"
	"os"
)

type Item struct {
	value    int // The value of the item; arbitrary.
	priority int // The priority of the item in the queue.
	// The index is needed by update and is maintained by the heap.Interface methods.
	index int // The index of the item in the heap.
}
type PriorityQueue []*Item

func (pq PriorityQueue) Len() int { return len(pq) }
func (pq PriorityQueue) Less(i, j int) bool {
	return pq[i].priority < pq[j].priority
}
func (pq PriorityQueue) Swap(i, j int) {
	pq[i], pq[j] = pq[j], pq[i]
	pq[i].index = i
	pq[j].index = j
}
func (pq *PriorityQueue) Push(x interface{}) {
	n := len(*pq)
	item := x.(*Item)
	item.index = n
	*pq = append(*pq, item)
}
func (pq *PriorityQueue) Pop() interface{} {
	old := *pq
	n := len(old)
	item := old[n-1]
	item.index = -1 // for safety
	*pq = old[0 : n-1]
	return item
}

type Q struct {
	pq *PriorityQueue
	ds map[int]int // It has always same value as pq. For random access.
}

func newQ() *Q {
	pq := new(PriorityQueue)
	heap.Init(pq)
	return &Q{
		pq: pq,
		ds: make(map[int]int),
	}
}
func (q *Q) pop() (u, d int) {
	item := heap.Pop(q.pq).(*Item)
	delete(q.ds, item.value)
	return item.value, item.priority
}
func (q *Q) get(u int) (int, bool) { // returns d
	d, ok := q.ds[u]
	return d, ok
}
func (q *Q) set(u, d int) {
	q.ds[u] = d
	for _, item := range *q.pq {
		if item.value != u {
			continue
		}

		item.priority = d
		heap.Fix(q.pq, item.index)
		return
	}
	heap.Push(q.pq, &Item{
		priority: d,
		value:    u,
	})
}
func (q *Q) len() int {
	return len(q.ds)
}

func main() {
	r := bufio.NewReader(os.Stdin)

	var n int
	fmt.Fscan(r, &n)
	cs := make([]map[int]int, n) // []v_i -> c_i
	for h := 0; h < n; h++ {
		var u, k int
		fmt.Fscan(r, &u, &k)
		m := make(map[int]int)
		for i := 0; i < k; i++ {
			var v, c int
			fmt.Fscan(r, &v, &c)
			m[v] = c
		}

		cs[u] = m
	}

	q := newQ()
	q.set(0, 0)
	visited := make(map[int]struct{})
	out := make([]int, n)

	for q.len() > 0 {
		u, d := q.pop()
		for uu, c := range cs[u] {
			// Consider the connection between u and uu.
			if _, ok := visited[uu]; ok {
				continue
			}
			dd := d + c
			if d, ok := q.get(uu); !ok || d > dd {
				q.set(uu, dd)
			}
		}

		out[u] = d
		visited[u] = struct{}{}
	}

	for u, d := range out {
		fmt.Println(u, d)
	}
}

Python: N = int(input())
G = [[] for i in range(N)]
for nod in range(N):
    tmp = list(map(int, input().split()))
    for i in range(2, tmp[1]*2+1, 2):
        edge, cos = tmp[i], tmp[i+1]
        G[nod].append([edge, cos])



import heapq


def dijkstra(x):
    d = [float('inf')] * N
    d[x] = 0
    visited = {x}

    # d, u
    hq = [(0, x)]

    while hq:
        u = heapq.heappop(hq)[1]
        visited.add(u)

        for node, cost in G[u]:
            if (node not in visited) and d[node] > d[u] + cost:
                d[node] = d[u] + cost
                heapq.heappush(hq, (d[u]+cost, node))
    return d


distance = dijkstra(0)
#print(distance)
for i in range(N):
    print(i, distance[i])

N = int(input())
G = [[] for i in range(N)]
for nod in range(N):
    tmp = list(map(int, input().split()))
    for i in range(2, tmp[1]*2+1, 2):
        edge, cos = tmp[i], tmp[i+1]
        G[nod].append([edge, cos])



import heapq


def dijkstra(x):
    d = [float('inf')] * N
    d[x] = 0
    visited = {x}

    # d, u
    hq = [(0, x)]

    while hq:
        u = heapq.heappop(hq)[1]
        visited.add(u)

        for node, cost in G[u]:
            if (node not in visited) and d[node] > d[u] + cost:
                d[node] = d[u] + cost
                heapq.heappush(hq, (d[u]+cost, node))
    return d


distance = dijkstra(0)
#print(distance)
for i in range(N):
    print(i, distance[i])

Python: import sys

f_i = sys.stdin

n = int(f_i.readline())

adj = [[(int(cost), int(v_n)) for v_n, cost in zip(x.split()[2::2], x.split()[3::2])] for x in f_i]

import heapq

def dijkstra():
    PQ = [(0, 0)]
    isVisited = [False] * n
    distance = [999900001] * n

    distance[0] = 0
    
    while PQ:
        uc = heapq.heappop(PQ)
        u = uc[1]

        if uc[0] > distance[u]:
            continue

        isVisited[u] = True
        
        for vc in adj[u]:
            v = vc[1]
            if isVisited[v] == True:
                continue
            t_cost = distance[u] + vc[0]
            if t_cost < distance[v]:
                distance[v] = t_cost
                heapq.heappush(PQ, (t_cost, v))

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


dijkstra()

Python: # coding: utf-8
# Your code here!
import heapq

WHITE = 0
GRAY = 1
BLACK = 2

INF = 2000000000


def dijkstra():
    PQ = []
    heapq.heapify(PQ)
    color = [WHITE] * n
    d = [INF] * n
    
    d[0] = 0
    heapq.heappush(PQ, (0, 0))
    color[0] = GRAY
    
    while len(PQ) != 0:
        
        f = heapq.heappop(PQ)
        u = f[1]
        color[u] = BLACK
        
        if d[u] < f[0]:
            continue
        
        for j in range(len(adj[u])):
            v = adj[u][j][0]
            if color[v] == BLACK:
                continue
            if d[v] > d[u] + adj[u][j][1]:
                d[v] = d[u] + adj[u][j][1]
                heapq.heappush(PQ, (d[v], v))
                color[v] = GRAY
    for i in range(n):
        print(i, d[i])


n = int(input())

adj = [[] for j in range(n)]
for i in range(n):
    nums=list(map(int,input().split()))
    for j in range(nums[1]):
        adj[nums[0]].append((nums[2*j+2], nums[2*j+3]))
        

dijkstra()

Python: N = int(input())

E = [None] * N
for _ in range(N):
    u, k, *vs = map(int, input().split())
    E[u] = []
    for i in range(k):
        v, c = vs[i*2], vs[i*2+1]
        E[u].append((v, c))

import heapq

vis = [False] * N
inf = 1e9
d = [inf] * N
d[0] = 0
pq = [(0, 0)]
while pq:
    nv, ni = heapq.heappop(pq)
    if nv > d[ni]:
        continue
    d[ni] = nv
    vis[ni] = True
    for v, c in E[ni]:
        nc = d[ni] + c
        if not vis[v] and nc < d[v]:
            heapq.heappush(pq, (nc, v))

for v in range(N):
    print(v, d[v])

Python: # -*- coding: utf-8 -*-
from heapq import heappop, heappush
def inpl(): return list(map(int, input().split()))
INF = float("inf")
N = int(input())
G = []
for _ in range(N):
    I = inpl()
    G.append(zip(*[I[3::2], I[2::2]]))

def dijkstra(G):
    C = [INF]*(N)
    C[0] = 0
    visited = [False] * (N)
    Q = [[0, 0]]

    while Q:
        c, u = heappop(Q)
        if C[u] < c:
            continue
        visited[u] = True
        for d, v in G[u]:
            if visited[v]:
                continue
            e = c + d
            if e < C[v]:
                C[v] = e
                heappush(Q, [e, v])
    return C

for i, c in enumerate(dijkstra(G)):
    print(i, c)

Python: import heapq as hp

INF = 1000000

def diikstraMethd(G, s):
    # ?????????
    n = len(G)
    d = [INF for _ in range(n)]
    d[s] = 0
    PQ = [(d[s], s)]

    while PQ:
        u = hp.heappop(PQ)[1]
        for v, c in G[u]:
            alt = d[u] + c
            if d[v] > alt:
                d[v] = alt
                hp.heappush(PQ, (alt, v))

    return d


if __name__ == '__main__':
    n = int(input())
    G = [ [] for _ in range(n)]
    for _ in range(n):
        tmp = list(map(int, input().split()))
        u = tmp.pop(0)
        k = tmp.pop(0)
        for i in range(k):
            v = tmp.pop(0)
            c = tmp.pop(0)
            G[u].append((v, c))

    d = diikstraMethd(G, 0)

    for i in range(n):
        print('{0} {1}'.format(i, d[i]))