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(raw_input())
G = [[-1] * n] * n
d = [0] * n
 
for i in range(n):
    v = map(int, raw_input().split())
    for j in range(v[1]):
        G[v[0]][v[2+2*j]] = int(v[3+2*j])
 
flag = [0] * n
tn = [0]
r = 0
while True:
    for i in range(n):
        if flag[i] == 0 and i in tn:
            flag[i] = 1
            d[i] = r
            for j in range(n):
                if G[i][j] != -1 and flag[j] == 0:
                    tn.append(j)
    if len(tn) == n:
        break
    r += 1
 
for i in range(n):
    print(str(i) + " " + str(d[i]))

Python: import sys
input = sys.stdin.readline


# import heapq
import heapq

# graph: 隣接リスト (頂点、距離）の順に格納
# start: 始点 (0-index)
# n: 頂点数
# memo[t]: startからtまでの最短距離
# return memo

def dijkstra(graph, start, n):
    INF = float('inf')
    memo = [INF] * n
    memo[start] = 0
    q = [(0, start)]

    while q:
        dist, ver = heapq.heappop(q)
        if memo[ver] < dist:
            continue
        for next_ver, next_dist in graph[ver]:
            if memo[next_ver] > dist + next_dist:
                memo[next_ver] = dist + next_dist
                heapq.heappush(q, (dist + next_dist, next_ver))

    return memo

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

memo = dijkstra(graph, 0, n)
for i, d in enumerate(memo):
    print(i, d)

Python: # -*- coding: utf-8 -*-


if __name__ == '__main__':

    n = int(input())
    M = [[float("inf") for j in range(n)] for i in range(n)]

    for i in range(n):
        l = list(map(int, input().split(" ")))
        for k in range(l[1]):
            j = l[2 + 2 * k]
            c = l[2 + 2 * k + 1]
            M[i][j] = c

    d = [float("inf")] * n

    def dijkstra(s):
        color = [0] * n
        p = [None] * n
        d[s] = 0
        p[s] = -1

        while True:
            mincost = float("inf")
            for i in range(n):
                if color[i] != 2 and d[i] < mincost:
                    mincost = d[i]
                    u = i

            if mincost == float("inf"):
                break

            color[u] = 2

            for v in range(n):
                if color[v] != 2:
                    if d[u] + M[u][v] < d[v]:
                        d[v] = d[u] + M[u][v]
                        p[v] = u
                        color[v] = 1

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

Python: import heapq


def dijkstra(g, source):
    n = len(g)
    q = []
    heapq.heapify(q)
    heapq.heappush(q, (0, source))
    d = [float('inf') for _ in range(n)]
    d[source] = 0
    while len(q) > 0:
        cur = heapq.heappop(q)
        cur_pos = cur[1]
        for next in g[cur_pos]:
            next_pos = next[0]
            next_d = d[cur_pos] + next[1]
            if next_d < d[next_pos]:
                d[next_pos] = next_d
                heapq.heappush(q, (d[next_pos], next_pos))
    return d


def main():
    n = int(input())
    g = [[] for _ in range(n)]
    for _ in range(n):
        inp = list(map(int, input().split()))
        m = inp[0]
        k = inp[1]
        for i in range(k):
            g[m].append((inp[(i+1)*2], inp[(i+1)*2+1]))
    d = dijkstra(g, 0)
    for i in range(n):
        print(i, d[i])


if __name__ == '__main__':
    main()

Python: from heapq import heapify, heappush, heappop
INF = float("inf")
def MAIN():
    n = int(input())
    G = [[i, INF] for i in range(n)]
    G[0][1] = 0
    m = {}
    for _ in range(n):
        A = list(map(int, input().split()))
        m[A[0]] = {}
        for i in range(2, len(A), 2):
            m[A[0]][A[i]] = A[i + 1]
    dp = [(0, 0)]
    while dp:
        cost, u = heappop(dp)
        for v, c in m[u].items():
            if G[v][1] > G[u][1] + c:
                G[v][1] = G[u][1] + c
                heappush(dp, (G[v][1], v))
    print("\n".join(" ".join(map(str, a)) for a in G))
MAIN()

Python: INFTY = 1 << 21
WHITE = 0
GRAY = 1
BLACK = 2
 
n = int(input())
M = [list(map(int, input().split())) for i in range(n)]
 
d = [INFTY for i in range(n)]
color = [INFTY for i in range(n)]
 
for i in range(n):
    u = int(input())
    k = int(input())
    for j in range(k):
        v = int(input())
        c = int(input())
        M[u][v] = c
        
def dijkstra():
    global M, d, p, color
    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
 
print(dijkstra())

Python: import sys
from collections import namedtuple
from heapq import heappop, heappush

Edge = namedtuple('Edage', 'to cost')
P = namedtuple('P', 'cost u')

N = int(input())

G = [[] for _ in range(N)]

for u in range(N):
  args = [int(x) for x in input().split()]
  #　不要な値を捨てる 
  args.pop(0)
  args.pop(0)

  while args:
    to = args.pop(0)
    cost = args.pop(0)
    G[u].append(Edge(to, cost))

costs = [sys.maxsize] * N
costs[0] = 0

q = [P(0, 0)]

while q:
  cost, u = heappop(q) 

  for v, c in G[u]:
    if costs[u] + c < costs[v]:
      costs[v] = costs[u] + c
      heappush(q, P(costs[v], v))

for i in range(N):
  print(i, costs[i])