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: n = int(input())
  from collections import defaultdict
  
  G = defaultdict(list)
  for i in range(n):
      i = [int(i) for i in input().split()]
      k = i[1]
      G[i[0]] = list(zip(i[2::2], i[3::2]))
  
  
  def mind(Q, d):
      c = float("inf")
      ret = 0
      for i, j in enumerate(d):
          if c > j and i in Q:
              c = j
              ret = i
      return ret
  
  
  def dijkstra(G):
      d = [0] + [float("inf")] * (n - 1)
      Q = set(range(n))
      while len(Q) != 0:
          u = mind(Q, d)
          print(u)
          Q = Q - set([u])
          for v, c in G[u]:
              if d[v] > d[u] + c:
                  d[v] = d[u] + c
      return d
  
  
  for i, j in enumerate(dijkstra(G)):
      print(i, j)
  
problem_description: Single Source Shortest Path
  
  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"}]