def getArrayInsertCharToStr(STR,CHAR):
  arr =[]
  s_len = len(STR)
  index =0
  while index <= s_len:
    #分割字符串
    arr.append(STR[:index]+CHAR+STR[index:s_len])
    index = index + 1
  return arr  

def getArrayInsertCharToArray(array,CHAR):
  index = 0
  re_array = []
  while index < len(array):
    re_array = re_array + getArrayInsertCharToStr(array[index],CHAR)
    index = index + 1
  return re_array       

def getPermutation(STR):
    resultArr = [STR[0]]
    for item in STR[1:]:
      resultArr = getArrayInsertCharToArray(resultArr,item)
    return   resultArr


print(getPermutation('abc'))