def generate(numRows):
def yhsj(i, j):
if i == 0 and j == 0:
return 1
elif i < 0 or j < 0:
return 0
else:
return yhsj(i-1, j-1) + yhsj(i-1, j)
def gen_row(row):
return [yhsj(row-1, i) for i in range(row)]
a = [gen_row(row) for row in range(numRows)]
a.pop(0)
return a