Go: package main

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

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

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

		out[u] = q[u]
		delete(q, u)
		visited[u] = struct{}{}
	}

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

func top(q map[int]int) int {
	minu := -1
	min := -1
	for u, d := range q {
		if min < 0 || d < min {
			minu = u
			min = d
		}
	}

	return minu
}

Python: import sys
inf = float('inf')

def debug(x, table):
    for name, val in table.items():
        if x is val:
            print('DEBUG:{} -> {}'.format(name, val), file=sys.stderr)
            return None

def SSSP(n, Adj):
    d = [inf] * n
    p = [-1] * n
    checked = [False] * n
    d[0] = 0
    checked[0] = True
    u = 0

    for i in range(n - 1):
        for v, cost in Adj[u]:
            if d[u] + cost < d[v]:
                p[v] = u
                d[v] = d[u] + cost

        min_n = 0
        min_w = inf
        for v in range(n):
            if not checked[v] and d[v] < min_w:
                min_n = v
                min_w = d[v]

        u = min_n
        checked[u] = True

    return d

def solve():
    n = int(input())
    Adj = [[] for i in range(n)]

    for i in range(n):
        u, k, *line = [int(i) for i in input().split()]
        for j in range(k):
            Adj[u].append((line[2*j], line[2*j + 1]))

    # debug(Adj, locals())

    d = SSSP(n, Adj)

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

if __name__ == '__main__':
    solve()

Python: import heapq

n = int(input())

adj = [[] for _ in range(n)]

for _ in range(n):
    tmp = list(map(int, input().split()))
    if tmp[1] != 0:
        node = tmp[0]
        for i in range(2, 2 + tmp[1] * 2, 2):
            adj[node].append((tmp[i], tmp[i + 1]))

def dijkstra(s):
    visited = [0]*n
    d = [float("inf")]*n
    
    visited[s] = 1
    d[s] = 0
    queue = [(0, s)]
    heapq.heapify(queue)
    
    while queue:
        mincost, u = heapq.heappop(queue)
        visited[u] = 2

        if d[u] >= mincost:
            for idx, i in adj[u]:
                if visited[idx] != 2 and d[idx] > d[u] + i:
                    d[idx] = d[u] + i
                    heapq.heappush(queue, (d[idx], idx))
                    visited[idx] = 1
                    
    for i in range(n):
        print(i, -1 if d[i] == float("inf") else d[i])


dijkstra(0)

Python: trial = int(input())
graph = []
for t in range(trial):
    graph.append([int(n) for n in input().split(" ")])
root = []
ans = []
stack = [[0,0]]
cnt = 0
while len(stack) > 0:
    index,out = stack[0][0],stack[0][1]
    for get in range(graph[index][1]):
        if graph[index][get*2 + 2] not in root:
            stack.append([graph[index][get*2 +2],graph[index][get*2 +3] + out ])
    if stack[0][0] not in root:
        root.append(stack[0][0])
        ans.append([str(stack[0][0]),str(stack[0][1])])
    stack.pop(0)
    stack = sorted(stack,key=lambda x:x[1])
ans = sorted(ans,key=lambda x:x[0])
for a in ans:
    print(" ".join(a))

Python: N = int(input())

#M[u][v]:隣接行列
M=[]
for n in range(N):
    input_temp=list(map(int,input().split()))
    M_temp=[-1]*N
    for k in range(0,2*input_temp[1],2):
        M_temp[input_temp[2+k]]=input_temp[2+k+1]
    M.append(M_temp)
    
#color:各頂点の訪問状態を示す
color=['white']*N

#d:TとV-Tを繋ぐ辺の中で重みが最小の辺の重みの値を保持
d=[10**10]*N

#p[v-1]:MSTにおけるvの親を保持
p=[-1]*N

#初期値
d[0] = 0
p[0] = -1

# ans=0
while True:
#     ans+=1
    mincost=10**10
    for i in range(N):
        if color[i] != 'BLACK' and d[i] < mincost:
            mincost = d[i]
            u = i
#     print(u,mincost)       
    if mincost == 10**10:
        break
    
    color[u] = 'BLACK'
    
    for v in range(N):
        if color[v] != 'BLACK' and M[u][v]!=-1:
#             print(u,v,color[v],M[u][v],d[v])
            if d[u]+M[u][v] < d[v]:
                d[v] = d[u] + M[u][v]
                p[v] = u
                color[v] = 'GRAY'
    # print(color,mincost,d,p)
    
for d_ in enumerate(d):
    print(d_[0],d_[1])

Python: N=int(input())
rinsetu=[[1000000 for i in range(N)] for j in range(N)]
d=[1000000]*(N)
color=["white"]*N
for i in range(N):
    a=list(map(int,input().split()))
    for j in range(a[1]):
        j1=j*2+2
        j2=j*2+3
        rinsetu[i][a[j1]]=a[j2]
def hunterhunter():
    d[0]=0
    while(True):
        mincost=1000000
        for i in range(N):
            if color[i]=="white" and mincost>d[i]:
                mincost=d[i]
                u=i
        if mincost==1000000:break
        color[u]="black"
        for i in range(N):
            if color[i]=="white" and rinsetu[u][i]!=1000000:
                if rinsetu[u][i]+d[u]<d[i]:
                    d[i]=rinsetu[u][i]+d[u]
hunterhunter()
for i,cost in enumerate(d):
    print(i,cost)

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(1, n+1):
    print(str(i) + " " + str(d[i]))

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 collections import deque

n = int(input())
g = []
d = [10**10] * n
d[0] = 0

for i in range(n):
    temp = list(map(int, input().split()))
    k = temp[1]
    temp = temp[2:]
    adj = []
    for j in range(k):
        v, c = temp[j*2], temp[j*2+1]
        adj.append([v, c])
    g.append(adj)

# for i in range(n):
#     print(g[i])

q = deque()
q.append((0, g[0]))
done = set()

while q:
    node = q.popleft()
    prev = node[0]
    adj = node[1]
    # print('\nadj:', adj)

    for next in adj:
        v = next[0]
        w = next[1]
        # print('v:', v)
        # print('prev:', prev)

        # d[v] = min(d[v], d[prev] + w)
        if d[prev] + w < d[v]:
            d[v] = d[prev] + w
            # Need to add to Q regardless of it's in done or not,
            # because the shortest path was udpated.
            q.append((v, g[v]))
        if v not in done:
            done.add(v)
            q.append((v, g[v]))

# print('d:', d)

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