An example of the Python Yang Hui triangle method

Program output requires the following effects:

[1] [About] [1,2,1] [1,3,3,1]

......

Method: Iteration, generator

def triangles ()    L = [1] While    True:        yiled L        =[1] + [l[i] + l[i+1] for I in range (len (L)-1)] + [1]n = 0fo R T in triangles ():    print (t)    n + = 1    if n = = Ten:        break

Implementation logic:

1. Since yield interrupts the output for the generator, it has the first output as [1]

2. Continue with the after yield loop, at which time the list length is 1, substituting it into the Len (L) in L, the [l[i]+l[i+1] for I in range (1-1)] is drawn as null, so the yield L output as [MAX]

3. At this time Len (L) value is 2, substituting [l[i]+l[i+1] for I in range (2-1)] is [l[i]+l[i+1] for I in range (1)],i can be evaluated as 0, substituting for [l[0]+l[1]], and l[0] and l[1] Has a value of 1 (as shown above), so the output is [1,2,1]

4. From the third article, The Len (L) value is 3, substituting [l[i]+l[i+1] for I in range (2)],i value 0 and 1, through the loop output has two values, all 3, respectively by [L[0]+l[1]],[l[1]+l[2]]