output_description: For each vertex, print its ID and the distance separated by a space character
  in a line respectively. Print in order of vertex IDs.
input_description: In the first line, an integer $n$ denoting the number of vertices in $G$ is
  given. In the following $n$ lines, adjacency lists for each vertex $u$ are
  respectively given in the following format:
  
  $u$ $k$ $v_1$ $c_1$ $v_2$ $c_2$ ... $v_k$ $c_k$
  
  Vertices in $G$ are named with IDs $0, 1, ..., n-1$. $u$ is ID of the target
  vertex and $k$ denotes its degree. $v_i (i = 1, 2, ... k)$ denote IDs of
  vertices adjacent to $u$ and $c_i$ denotes the weight of a directed edge
  connecting $u$ and $v_i$ (from $u$ to $v_i$).
attempt: 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])
  
problem_description: Single Source Shortest Path II
  
  For a given weighted graph $G = (V, E)$, find the shortest path from a source
  to each vertex. For each vertex $u$, print the total weight of edges on the
  shortest path from vertex $0$ to $u$.
samples: [{"input": "5\n    0 3 2 3 3 1 1 2\n    1 2 0 2 3 4\n    2 3 0 3 3 1 4 1\n    3 4 2 1 0 1 1 4 4 3\n    4 2 2 1 3 3", "output": "0 0\n    1 2\n    2 2\n    3 1\n    4 3"}]