Python杨辉三角算法

#!/usr/bin/env python
# -*- coding: utf-8 -*-
def triangles():
      n = 1
      aboveList = []
      while True:
          if n == 1:
              aboveList = [1]
              n = n + 1
              yield [1]
          if n == 2:
              aboveList = [1,1]
              n = n + 1
              yield [1,1]
          newList = []
          for x in getMiddleList(aboveList):
              newList.append(x)
          newList.insert(0,1)
          newList.append(1)
          aboveList = newList
          n = n + 1
          yield newList
      return ‘done‘

def getMiddleList(aboveList):
    newList = []
    leftNodeVal=0 
    n=1
    for x in aboveList:
        if n == 1:
            leftNodeVal = x
        else:
            newList.append(x+leftNodeVal)
            leftNodeVal = x
        n += 1
    return newList

n=0
for t in triangles():
    print(t)
    n = n + 1
    if n == 10:
        break