Go: package main

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

const BIG_COST = 200000

type Path struct {
	node int
	cost int
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)

	nNodes := scanInt(sc)

	// 各頂点につながる頂点一覧を得るための隣接リスト
	graph := make([][]Path, nNodes)

	for i := 0; i < nNodes; i++ {
		u := scanInt(sc)
		k := scanInt(sc)
		graph[i] = make([]Path, k)
		for d := 0; d < k; d++ {
			graph[u][d] = Path{
				node: scanInt(sc),
				cost: scanInt(sc),
			}
		}
	}

	// 0 から各頂点への最小コストを保存する配列
	minCosts := make([]int, nNodes)

	minCosts[0] = 0
	for i := 1; i < nNodes; i++ {
		minCosts[i] = BIG_COST
	}

	// 各頂点が調査済みかどうかを保持する配列
	checked := make([]bool, nNodes)

	// 最小コストのパスを高速に取得するためのヒープ。
	// コストが小さいものほどルートに来るようにする。
	heap := NewHeap(func(a, b Path) bool {
		return a.cost < b.cost
	})

	heap.insert(Path{node: 0, cost: 0})
	for heap.size > 0 {
		u := heap.extractMax()

		// 隣接行列を使っていた時とは違い、ヒープには
		// 同じノードへのパスが複数含まれうる。そのため既によりコストの低い
		// パスが見つかっている場合は無視する。
		if minCosts[u.node] < u.cost {
			continue
		}

		checked[u.node] = true

		for _, v := range graph[u.node] {
			cost := v.cost + u.cost
			if !checked[v.node] && cost < minCosts[v.node] {
				minCosts[v.node] = cost
				heap.insert(Path{node: v.node, cost: cost})
			}
		}
	}

	w := bufio.NewWriter(os.Stdout)
	for i, cost := range minCosts {
		fmt.Fprintf(w, "%d %d\n", i, cost)
	}
	w.Flush()
}

func scanInt(sc *bufio.Scanner) int {
	sc.Scan()
	v, _ := strconv.Atoi(sc.Text())
	return v
}

// --- From ALDS1_9_C: Priority Queue

type Heap struct {
	size   int
	heap   []Path
	isHigh func(a, b Path) bool
}

func NewHeap(isHigh func(a, b Path) bool) Heap {
	heap := make([]Path, 1) // 先頭は不使用
	return Heap{size: 0, heap: heap, isHigh: isHigh}
}

func (h *Heap) insert(v Path) {
	h.size += 1
	if h.size > len(h.heap)-1 {
		h.heap = append(h.heap, v)
	} else {
		h.heap[h.size] = v
	}

	for i := h.size; i > 1; {
		parent := i / 2
		if h.isHigh(h.heap[parent], h.heap[i]) {
			break
		}
		h.heap[i], h.heap[parent] = h.heap[parent], h.heap[i]
		i = parent
	}
}

func (h *Heap) extractMax() Path {
	if h.size <= 0 {
		panic("cannot extract from empty heap")
	}

	max := h.heap[1]
	h.heap[1] = h.heap[h.size]
	h.size -= 1
	h.maxHeapify(1)

	return max
}

func (h *Heap) maxHeapify(idx int) {
	left := idx * 2
	right := left + 1
	largest := idx

	if left <= h.size {
		if h.isHigh(h.heap[left], h.heap[idx]) {
			largest = left
		}
		if right <= h.size && h.isHigh(h.heap[right], h.heap[largest]) {
			largest = right
		}
	}

	if largest != idx {
		h.heap[idx], h.heap[largest] = h.heap[largest], h.heap[idx]
		h.maxHeapify(largest)
	}
}

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)]
    distance = [999900001] * n

    distance[0] = 0
    
    while PQ:
        uc = heapq.heappop(PQ)
        u = uc[1]
        
        for vc in adj[u]:
            v = vc[1]
            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: from sys import stdin
import heapq
INF = 1<<21
n = int(stdin.readline())
adj = [[]] * n
for u in range(0, n):
    U = list(map(int, stdin.readline().split()[2:]))
    adj[u] = zip(U[0::2], U[1::2])
def dijkstra():
    d = [0] + [INF] * (n - 1)
    hq = [(0, 0)]
    while hq:
        u = heapq.heappop(hq)[1]
        for v, c in adj[u]:
            alt = d[u] + c
            if d[v] > alt:
                d[v] = alt
                heapq.heappush(hq, (alt, v))
    for i, c in enumerate(d):
        print(i, c)
dijkstra()

Python: from queue import PriorityQueue

def sssp(adj_list):
    n = len(adj_list)
    d = [None]*n
    pq = PriorityQueue()
    pq.put((0, 0)) # d, v

    while(not pq.empty()):
        d_v, v = pq.get()
        if d[v] is not None:
            continue
        d[v] = d_v
        for u, c_vu in adj_list[v]:
            pq.put((d[v]+c_vu, u))

    return d


if __name__ == '__main__':
    n = int(input())
    adj_list = []
    for _ in range(n):
        adj_list.append([])

    for _ in range(n):
        l = list(map(int, input().rstrip().split(' ')))
        u = l[0]
        k = l[1]
        adj_list_for_u = []
        for v, c in zip(l[2::2], l[3::2]):
            adj_list_for_u.append((v,c))
        adj_list[u] = adj_list_for_u

    d = sssp(adj_list)
    for u, d_u in zip(range(n), d):
        print (u, d_u)

Python: from heapq import heappop, heappush

def dijkstra(s):
    dp[s] = 0
    hq = []
    used[s] = 0
    for i in cost[s]:
        heappush(hq, i)

    while hq:
        minv = heappop(hq)
        if used[minv[1]] == 0:
            continue
        v = minv[1]
        dp[v] = minv[0]
        used[v] = 0
        for i in cost[v]:
            if used[i[1]]:
                heappush(hq, [i[0] + dp[v], i[1]])
    return

INF = 10 ** 18
n = int(input())
cost = [[] for _ in range(n)]
used = [1] * n
dp = [INF] * n

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

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

Python: #!/usr/bin/env python3
import sys
import heapq
input = lambda: sys.stdin.readline()[:-1]
sys.setrecursionlimit(10**8)
inf = float('inf')
mod = 10**9+7

n=int(input())
G=[[] for i in range(n)]
for _ in range(n):
    inp = list(map(int,input().split()))
    u,k=inp[:2]
    for i in range(k):
        G[u].append((inp[2+2*i],inp[3+2*i]))

def disktra(g,s):
    n=len(g)
    dist = [inf]*n
    dist[s] = 0
    hq=[]
    heapq.heappush(hq,(dist[s],s))
    while hq:
        cost,u =heapq.heappop(hq)
        if dist[u] < cost:
            continue
        for v,c in g[u]:
            if dist[v] <= dist[u] +c:
                continue
            dist[v] = dist[u] + c
            heapq.heappush(hq,(dist[v],v))
    return dist

d=disktra(G,0)
for i in range(n):
    print(i,d[i])

Python: import queue

def dijkstra(s):
    color = ["white"]*n
    d = [float('inf')]*n
    d[s] = 0
    
    pq = queue.PriorityQueue()
    
    pq.put((0,s))
    
    while not pq.empty():
        u = pq.get()
        color[u[1]] = "black"
        
        if d[u[1]] < u[0]:
            continue
            
        for v,w in zip(Adj[u[1]][2::2],Adj[u[1]][3::2]):
            if color[v] != "black":
                if d[u[1]] + w < d[v]:
                    d[v] = d[u[1]]+w
                    color[v] = "gray"
                    pq.put((d[v],v))
                    
    return d

n = int(input())
Adj = [list(map(int,input().split())) for _ in range(n)]
ans = dijkstra(0)

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