message: Update kill-process.py
diff: # Time: O(n)
  # Space: O(n)
  -# Given n processes, each process has a unique PID (process id)
  -# and its PPID (parent process id).
  -#
  -# Each process only has one parent process, but may have one or more children processes.
  -# This is just like a tree structure. Only one process has PPID that is 0,
  -# which means this process has no parent process. All the PIDs will be distinct positive integers.
  -#
  -# We use two list of integers to represent a list of processes,
  -# where the first list contains PID for each process
  -# and the second list contains the corresponding PPID.
  -#
  -# Now given the two lists, and a PID representing a process you want to kill,
  -# return a list of PIDs of processes that will be killed in the end.
  -# You should assume that when a process is killed,
  -# all its children processes will be killed.
  -# No order is required for the final answer.
  -#
  -# Example 1:
  -# Input:
  -# pid = [1, 3, 10, 5]
  -# ppid = [3, 0, 5, 3]
  -# kill = 5
  -# Output: [5,10]
  -# Explanation:
  -# 3
  -# / \
  -# 1 5
  -# /
  -# 10
  -# Kill 5 will also kill 10.
  -# Note:
  -# The given kill id is guaranteed to be one of the given PIDs.
  -# n >= 1.
  -
  # DFS solution.
  class Solution(object):
  def killProcess(self, pid, ppid, kill):
  