text: import random, json, requests
  from hashlib import sha256
  
  N = 16
  
  class Graph:
      def __init__(self, size):
          self.size = size
          self.adj_mat = [[False for _ in range(0, size)] for _ in range(0, size)]
  
      def from_hash(hash):
          graph = Graph(N)
  
          i = 0
  
          for byte in hash.digest():
              if i > 25:
                  break
  
              u = byte >> 4
              v = byte & 0xf
              # print(bin(byte), u, v)
              # Use four bit sized numbers to represent nodes
              graph.connect(u, v)
  
              i += 1
  
          return graph
  
      def verify_path(self, path: list[int]) -> bool:
          # is_connected returns True if u is None
          u = None
          for v in path:
              if not self.is_connected(u, v):
                  return False
              u = v
          return True
  
      def print(self):
          for i in range(0, N):
              print(i, '->', end = ' ')
              for j in range(0, N):
                  if i != j and self.is_connected(i, j):
                      print(j, end = ' ')
              print()
  
  
      def connect(self, u: int, v: int):
          self.adj_mat[u][v] = True
  
      def is_connected(self, u: int, v: int) -> bool:
          if u == None:
              return True
          return self.adj_mat[u][v]
  
  NOT_IN_STACK = -1
  
  def dfs(u: int, graph: Graph, label: list[int], instack_count: int) -> int:
      if instack_count == graph.size:
          return u
  
      for v in range(0, graph.size):
          if graph.is_connected(u, v) and label[v] == NOT_IN_STACK:
              label[v] = u
  
              res = dfs(v, graph, label, instack_count + 1)
              if res >= 0:
                  return res
  
              label[v] = NOT_IN_STACK
  
      return -1
  
  def find_hamiltonian_path(graph: Graph) -> list[int]:
      path = [NOT_IN_STACK for _ in range(0, graph.size)]
      end = dfs(None, graph, path, 0)
      # is_connected returns True if u is None
  
      # print('PARENT PATH:', path)
  
      if end < 0:
          return None
  
      sequence = [None for _ in range(0, graph.size)]
  
      for i in range(graph.size - 1, -1, -1):
          sequence[i] = end
          end = path[end]
  
      return sequence
  