[英]This is a question about lists in python. Can we concatenate two lists
n=int(input("Enter number of rows: "))
a=[]
for i in range(n):
a.append([])
a[i].append(1)
for j in range(1,i):
a[i].append(a[i-1][j-1]+a[i-1][j])
if(n!=0):
a[i].append(1)
for i in range(n):
print(" "*(n-i),end=" ",sep=" ")
for j in range(0,i+1):
print('{0:6}'.format(a[i][j]),end=" ",sep=" ")
print()
I'm trying to learn to print a pascal triangle, got struck at one line 我正在努力学习打印一个帕斯卡三角形,在一条线上被击中
a[i].append(a[i-1][j-1]+a[i-1][j])
is the above line what does the line do. 上面这行是做什么的。 can anyone explain a[i-1][j-1] does? 任何人都可以解释[i-1] [j-1]吗?
Note that a
is a list of list where a[i]
is the i-th row of the Pascal's triangle. 注意a
是列表,其中a[i]
是Pascal三角形的第i行。
a[i][j]
stores the j-th element of the i-th row of the Pascal's triangle, it is an int. a[i][j]
存储Pascal三角形的第i行的第j个元素,它是一个int。
They are just using the formula of Pascal's triangle . 他们只是使用Pascal三角形的公式。
a[i][j] = a[i-1][j-1] + a[i-1][j]
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