KMP算法-字符串匹配算法

没搞懂，先记下来

def KMP(string, pattern):
  tnext = get_next(pattern)
  i = 0
  j = 0
  while i < len(string) and j < len(pattern):
    if j == -1 or string[i] == pattern[j]:
      i += 1
      j += 1
    else:
      j = tnext[j]
  if j >= len(pattern):
    return i - len(pattern)
  else
    return -1
def get_next(pattern):
  tnext = []
  for i in range(len(pattern)):
    tnext.append(0)
  tnext[0] = -1
  j = 0
  k = -1
  while j < len(pattern)-1:
    if k == -1 or pattern[j] == pattern[k]:
      j += 1
      k += 1
      tnext[j] = k
    else:
      k = tnext[k]
  return tnext
print KMP('efababc', 'ababc')