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: from heapq import heappop, heappush

def dijkstra1(g, source):
    # O(ElogV)

    n = len(g)
    inf = float("inf") # 高速化のためにはfloat("inf")ではないほうがいい
    dist = [inf] * n
    dist[source] = 0
    q = [(0, source)]

    while q:
        cost, u = heappop(q)
        if dist[u] < cost:
            continue
        for c, v in V[u]:
            if dist[v] > dist[u] + c:
                dist[v] = dist[u] + c
                heappush(q, (dist[v], v))

    return dist

def dijkstra2(g, source):
    n = len(V)
    inf = float("inf") # 高速化のためにはfloat("inf")ではないほうがいい
    used = [False]*n
    dist = [inf]*n
    dist[0] = 0
    
    for _ in range(n):
        c1, u = min([(dist[i], i) for i in range(n) if not used[i]])
        used[u] = True
        for c2, v in V[u]:
            if v==u: continue
            dist[v] = min(dist[v], c1+c2)
    return dist


if __name__ == "__main__":
    n = int(input())
    V = [[] for _ in range(n)]

    for _ in range(n):
        u, k, *vc = map(int, input().split())
        for i in range(0, 2*k, 2):
            v, c = vc[i], vc[i+1]
            V[u].append((c, v))

    d = dijkstra2(V, 0)
    for i, j in enumerate(d):
        print(i, j)

Python: import heapq

def dijkstra(graph, weights, s):
    d = {u: float('inf') for u in graph}
    d[s] = 0
    queue = []
    heapq.heappush(queue, (0, s))
    while queue:
        w, u = heapq.heappop(queue)
        for v in graph[u]:
            d_temp = d[u] + weights[u, v]
            if d[v] > d_temp:
                d[v] = d_temp
                heapq.heappush(queue, (d_temp, v))
    return d

n = int(input())
graph, weights = {}, {}
for _ in range(n):
    line = input().split()
    neighbors = []
    for i in range(0, 2 * int(line[1]), 2):
        neighbors.append(line[2+i])
        weights[line[0], line[2+i]] = int(line[3+i])
    graph[line[0]] = neighbors

d = dijkstra(graph, weights, '0')

for i in range(n):
    print(i, d[str(i)])

Python: n=int(input())
M=[[-1]*n for _ in[0]*n]
for _ in[0]*n:
 e=list(map(int,input().split()))
 for i in range(e[1]):k=2*-~i;M[e[0]][e[k]]=e[k+1]
d=[0]+[1e6]*~-n
c=[1]*n
while 1:
 m,u=1e6,-1
 for i in range(n):
  if m>d[i]and c[i]:m,u=d[i],i
 if u<0:break
 c[u]=0
 for v in range(n):
  if c[v]and 1+M[u][v]and d[v]>d[u]+M[u][v]:
   d[v]=d[u]+M[u][v]
for i in range(n):print(i,d[i])

Python: import heapq

n=int(input())
u=[0]*n
k=[0]*n
v=[0]*n
z=[[] for _ in range(n) ]
for i in range(n):
  u[i],k[i],*v[i] = map(int,input().split())
  for j in range(0,len(v[i]),2):
    z[i].append([v[i][j],v[i][j+1]])
d=[float("inf")]*n 
e=[-1] *n #いったことなければ -1


def dijkstra(x):
  e[x]=0 #ブクマ
  d[x]=0
  q= [ (d[x],x) ] 
  
  while len(q)>0:
    #print(d)
    b,a = heapq.heappop(q)
    e[a]=0
    
    if d[a] < b:
      pass
    else:
      to_go = z[a]
      for s,t in to_go:
        if e[s]==0:
          pass
        else:
          if d[s] > d[a]+t :
            d[s] = d[a]+t
            heapq.heappush( q, (d[s],s) )

  
dijkstra(0)
for i in range(n):
  print(i,d[i])

Python: import queue
from sys import maxsize as INFTY
from collections import namedtuple
Q = namedtuple("Q", "u c")

n = int(input())
dic = {}

for _ in range(n):
    a = [int(x) for x in input().split()]
    a.reverse()

    u, k = a.pop(), a.pop()
    for _ in range(k):
        v, c = a.pop(), a.pop()
        dic[(u, v)] = c


def bfs(n, s):
    res = [INFTY] * n
    q = queue.Queue()
    q.put(Q(s, 0))

    while q.qsize() != 0:
        p = q.get()
        if res[p.u] <= p.c: continue
        res[p.u] = p.c

        for i in range(n):
            if i == p.u: continue
            v = (p.u, i)
            if v not in dic: continue
            q.put(Q(i, p.c + dic[v]))
    return res


ans = bfs(n, 0)
for i in range(n):
    print(i, ans[i])

Python: from collections import defaultdict

def dijkstra(G, s):
  heap = Heap()
  heap.push((s, 0))
  fixed = set()
  d = defaultdict(lambda: 999999999999999999999)
  d[s] = 0
  while len(heap.data) > 0:
    v = heap.pop()
    if v in fixed:
      continue
    for u in G[v]:
      if u in fixed:
        continue
      c = G[v][u]
      if d[v] + c < d[u]:
        d[u] = d[v] + c
        heap.push((u, d[u]))
    fixed.add(v)
  return d


class Heap:
  def __init__(self):
    self.data = []

  def push(self,x):
    self.data.append(x)
    i = len(self.data)-1
    while self._p(i) >= 0:
      if self.data[i][1] < self.data[self._p(i)][1]:
        tmp = self.data[i]
        self.data[i] = self.data[self._p(i)]
        self.data[self._p(i)] = tmp
        i = self._p(i)
      else:
        break

  def pop(self):
    ret = self.top()
    n = self.data.pop()
    if len(self.data) > 0:
      self.data[0] = n
      i = 0
      while True:
        if self._l(i) < len(self.data):
          l = self.data[self._l(i)]
        else:
          l = (-1, 999999999999999999999)
        if self._r(i) < len(self.data):
          r = self.data[self._r(i)]
        else:
          r = (-1, 999999999999999999999)
        if l[1] > r[1]:
          if r[1] < self.data[i][1]:
            tmp = self.data[i]
            self.data[i] = self.data[self._r(i)]
            self.data[self._r(i)] = tmp
            i = self._r(i)
          else:
            break
        else:
          if l[1] < self.data[i][1]:
            tmp = self.data[i]
            self.data[i] = self.data[self._l(i)]
            self.data[self._l(i)] = tmp
            i = self._l(i)
          else:
            break
    return ret[0]

  def top(self):
    return self.data[0]

  def _p(self, i):
    i = i+1
    return i//2-1

  def _l(self, i):
    i = i+1
    return i*2-1

  def _r(self, i):
    i = i+1
    return i*2


G = {}

n = int(input())
for _ in range(n):
  entry = [int(v) for v in input().strip().split(' ')]
  u = entry[0]
  k = entry[1]
  G[u] = {}
  for i in range(k):
    v = entry[2+i*2]
    c = entry[3+i*2]
    G[u][v] = c

d = dijkstra(G, 0)

for i in range(n):
  print(i, d[i])