不得不说，CS61A的作业是真硬啊，一个LAB我做了一晚上。测试题目的话就不贴了。老教授好像还没教到debugger的那一块，所以error测试的时候,其实半懂不懂的.
所以直接贴题目了,有些题目,我觉得应该有更好的写法.我写的繁琐的紧了.
01 falling n数之积;
def falling(n, k):
"""Compute the falling factorial of n to depth k.
>>> falling(6, 3) # 6 * 5 * 4
120
>>> falling(4, 3) # 4 * 3 * 2
24
>>> falling(4, 1) # 4
4
>>> falling(4, 0)
1
"""
"*** YOUR CODE HERE ***"
这一题,我写了很久.这题最重要的点在于k的值从什么时候终止.我一直就想k -= 1的方式去做,但是试了好几次,都不行,只好加了一个临时变量了;
def falling(n, k):
"""Compute the falling factorial of n to depth k.
>>> falling(6, 3) # 6 * 5 * 4
120
>>> falling(4, 3) # 4 * 3 * 2
24
>>> falling(4, 1) # 4
4
>>> falling(4, 0)
1
"""
"*** YOUR CODE HERE ***"
total = 1
if not k:
return 1
else:
counter = 0
while k - counter:
total *= n # 6 5 4
n -= 1
counter += 1 # 1 2 3
return total
02 sum_digits 各位数之和
def sum_digits(y):
"""Sum all the digits of y.
>>> sum_digits(10) # 1 + 0 = 1
1
>>> sum_digits(4224) # 4 + 2 + 2 + 4 = 12
12
>>> sum_digits(1234567890)
45
>>> a = sum_digits(123) # make sure that you are using return rather than print
>>> a
6
"""
"*** YOUR CODE HERE ***"
这题就不复杂了,只要取余求出各位数的值,然后相加就行了,但是有个问题就是10,因为10/10 = 0 的原因,需要考虑这种特殊情况;其余的迭代就行.
def sum_digits(y):
"""Sum all the digits of y.
>>> sum_digits(10) # 1 + 0 = 1
1
>>> sum_digits(4224) # 4 + 2 + 2 + 4 = 12
12
>>> sum_digits(1234567890)
45
>>> a = sum_digits(123) # make sure that you are using return rather than print
>>> a
6
"""
"*** YOUR CODE HERE ***"
sum_t = 0
while y:
if y == 1:
sum_t += 1
else:
sum_t += y % 10
y = y // 10
return sum_t
03 double_eights 判断连续两个值是否都为8;
def double_eights(n):
"""Return true if n has two eights in a row.
>>> double_eights(8)
False
>>> double_eights(88)
True
>>> double_eights(2882)
True
>>> double_eights(880088)
True
>>> double_eights(12345)
False
>>> double_eights(80808080)
False
"""
"*** YOUR CODE HERE ***"
这一题,我原来的做法是
if n % 10 == 8 and n % 100 == 8: # 这种判断88 % 100 的时候余数应该是88.这种写法是错误的;
正确写法是这样,虽然复杂,但是能通过;
def double_eights(n):
"""Return true if n has two eights in a row.
>>> double_eights(8)
False
>>> double_eights(88)
True
>>> double_eights(2882)
True
>>> double_eights(880088)
True
>>> double_eights(12345)
False
>>> double_eights(80808080)
False
"""
"*** YOUR CODE HERE ***"
while n:
if n % 10 == 8:
y = n // 10
if y % 10 == 8:
return True
n = n // 10
return False
最后,补个截图.第一次lab通过了:
