习题解析

0.打印10以内偶数：位运算

for i in range(10):

if not i & 0x01:

print(i)

1.给定一个不超过5位的正整数，判断其有几位(使用input函数)

方法一：正常逻辑处理

a = int(input("Please enter a numer: "))

if a < 0:

print('Error')

if a < 10:

print(1)

elif a < 100:

print(2)

elif a < 1000:

print(3)

elif a < 10000:

print(4)

elif a < 100000:

print(5)

else:

print('Error')

方法二：折半

a=int(input("Please enter a numer: "))

if a < 0:

print('Error')

elif a < 1000:

if 9 < a < 100:

print(2)

elif a < 10:

print(1)

else:

print(3)

elif a < 10000:

print(4)

elif a < 100000:

print(5)

else:

print('Error')

方法三：字符串处理

a = str(int(input("Please enter a number: ")))

print(len(a))

2.给定一个不超过5位的正整数，判断该数的位数，依次打印出个位、十位、百位、千位、万位的数字

方法一：

a = int(input("Please enter a number: "))

length = 0

if a < 0:

print('Error')

elif a < 1000:

if 9 < a < 100:

length = 2

elif a < 10:

length = 1

else:

length = 3

elif a < 10000:

length = 4

elif a < 100000:

length = 5

else:

print('Error')

print(length)

for i in range(length):

print(a % 10)

a = a // 10

方法二：

a = input("Please enter a number: ")

b = int(a)

print(len(a))

for i in range(len(a)):

print(b % 10)

b = b // 10

方法三：

a = int(input("Please enter a number: "))

length = 0

if a < 0:

print('Error')

elif a < 1000:

if 9 < a < 100:

length = 2

elif a < 10:

length = 1

else:

length = 3

elif a < 10000:

length = 4

elif a < 100000:

length = 5

else:

print('Error')

print(length)

for i in range(length):

print(a - (a // 10) * 10)

a = a // 10

方法四：

a=int(input("Please enter a number: "))

a *= 10

while (a // 10) != 0:

a //= 10

print(a % 10)

3.给定一个不超过5位的正整数，判断该数的位数，依次打印出万位、千位、百位、十位、个位的数字

方法一：

a=input('Please enter a number: ')

b=int(a)

for i in range(len(a),0,-1):

te = 10 ** (i - 1)

c = b // te

print(c)

b -= (c * te)

print(len(a))

方法二：

a = int(input("Please enter a number: "))

length = 0

if a < 0:

print('Error')

elif a < 1000:

if 9 < a < 100:

length = 2

elif a < 10:

length = 1

else:

length = 3

elif a < 10000:

length = 4

elif a < 100000:

length = 5

else:

print('Error')

print(length)

pre = 0

for i in range(length,0,-1):

cur = a // (10 ** (i - 1))

print(cur - pre * 10)

pre = cur

方法三：

a = int(input("Please enter a number: "))

length = 0

if a < 0:

print('Error')

elif a < 1000:

if 9 < a < 100:

length = 10

elif a < 10:

length = 1

else:

length = 100

elif a < 10000:

length = 1000

elif a < 100000:

length = 10000

else:

print('Error')

while length:

print(a // length)

a %= length

length //= 10

方法四：

c = int(input("Please enter a number: "))

w = 10000

length = 5

flag = False

while w:

t = c // w

if flag:

print(t)

else:

if t:

print(t)

flag = True

else:

length -= 1

c = c % w

w //= 10

print("The length of number is", length)

4.打印一个边长为n的正方形

方法一：

a = int(input("Please enter a number: "))

for i in range(a):

if i == 0 or i == a-1:

print('*' * a )

else:

print('*' + ' ' * (a - 2) + '*')

方法二：

a = int(input("Please enter a number: "))

print('*' * a)

for i in range(a - 2):

print('*' + ' ' * (a - 2) + '*')

else:

print('*' * a)

方法三：

a = int(input("Please enter a number: "))

top = mid = '*'

for i in range(a - 1):

top += '\t*'

mid += '\t'

else:

mid += '*'

print(top)

for i in range(a - 2):

print('\n')

print(mid)

else:

print('\n')

print(top)

5.求100内所有奇数的和(2500)

方法一：

sum = 0

for i in range(1,100,2):

sum += i

print(sum)

6.判断学生成绩，成绩等级A~E。其中，90分以上为'A'，80~89分为'B'，70~79分为'C'，60~69分为'D'，60分以下为'E'

方法一：

a = int(input('Please enter a score: '))

if a > 79:

if a >= 90:

print('A')

else:

print('B')

elif a >= 70:

print('C')

elif 60 <= a < 69:

print('D')

else:

print('E')

7.求1到5阶乘之和

方法一：

sum = 0

for i in range(1,6):

mul = 1

for j in range(1,i + 1):

mul *= j

sum += mul

print(sum)

方法二：效率高

sum = 0

mul = 1

for i in range(1,6):

mul *= i

sum += mul

print(sum)

8.给一个数，判断它是否是素数(质数)

a=int(input("Please enter a number: "))

for i in range(2,int(a ** 0.5) + 1):

if a % i != 0:

continue

elif a % i == 0:

print(("N: %d") % (i))

break

else:

print("Yes,prime")

9.打印九九乘法表

for i in range(1,10):

line = ''

for j in range(1,i + 1):

line = line + ('%d*%d=%2d ') % (j,i,i*j)

print(line)

10.打印菱形

方法一：

a = int(input(">>>"))

b = (a - 1) / 2

for i in range(a):

if i <= b:

print(' ' * ((a - (2 * i + 1)) // 2) +'*' * (i * 2 + 1) + ' ' * (( a - (2 * i + 1)) // 2 ))

else:

m=int(2 * b - i)

print(' '*((a - (2 * m + 1)) // 2) +'*' * (m * 2 + 1) +' ' * ((a - (2 * m + 1)) // 2))

方法二：

a = int(input(">>>"))

b=(a - 1) // 2

for i in range(-b,b + 1):

c = abs(i)

print(' ' * c + '*' * (a - 2 * c) + ' ' * c)

11.打印100以内的斐波那契数列

a = 1

b = 1

while True:

ne = a + b

if ne >= 100:

break

a = b

b = ne

print(ne)

12.求斐波那契数列第101项 573147844013817084101

a = 1

b = 1

cnt = 2

while True:

ne = a + b

a = b

b = ne

cnt += 1

if cnt == 101:

print(b)

break

13.求10万内的所有素数 9592

方法一：

import datetime

start=datetime.datetime.now()

cnt=1

for i in range(3,100000,2):#优化点1：排除偶数

for j in range(3,int(i ** 0.5) + 1,2):#优化点2：排除含有因子2的数并只循环到原数的开方加1

if i % j == 0:

break

else:

#print(i)

cnt += 1

end=(datetime.datetime.now() - start).total_seconds()

print(end)

print(cnt)

方法二：

a = int(input('>>>'))

import datetime

start=datetime.datetime.now()

cnt = 2

for i in range(4,a):

if i % 6 != 1 and i % 6 != 5:#质数必与6的倍数相邻

continue

else:

for j in range(5,int(i ** 0.5) + 1,2):

if i % j == 0:

break

else:

cnt += 1

end=(datetime.datetime.now()-start).total_seconds()

print(end)

print(cnt)

方法三：

x = 5

step = 2

count = 2

while x < 100000:

for i in range(3,int(x ** 0.5) + 1,2):

if not x % i:

break

else:

count += 1

x += step

step = 4 if step == 2 else 2

print(count)

方法四：

prime=[2]

for i in range(3,100000,2):

flag=False

up=int(i**0.5)+1

for j in prime:

if i%j==0:

flag=False

break

if j>=up:

flag=True

break

if flag:

prime.append(i)

print(len(prime))

方法五：

筛选法

待补充

14.输入若干整数，打印最大值：

temp = 0

while True:

a = input('>>>')

if not a:

temp = a

break

else:

b = int(a)

if b >= temp:

temp = b

print(temp)

15.输入n个数，求每次输入后的算数平均数

sum = 0

cnt = 0

while True:

a = input('>>>')

if not a:

break

else:

sum += float(a)

cnt += 1

print(sum / cnt)

16.反向乘法表：

方法一：

for i in range(1,10):

line = ''

for j in range(i,10):

line += '%d*%d=%2d ' % (i,j,j * i)

print(' ' * (7 * i - 6) + line)

方法二：

for i in range(1,10):

line = ''

for j in range(i,10):

line += '%d*%d=%2d ' % (i,j,j * i)

print('{:>63}'.format(line))

方法三：

for i in range(1,10):

line = ''

for j in range(i,10):

line += '{}*{}={:

print('{:>70}'.format(line))

17.打印对顶三角形：

a = int(input(">>>"))

b = (a - 1) // 2

for i in range(-b,b + 1):

c = int((a - (2 * abs(i) + 1)) / 2)

print(' ' * c + '*' * (2 * abs(i) + 1) + ' ' * c)

18.打印闪电：

num = int(input(">>>"))

if num % 2 == 0:

num += 1

half = (num - 1) // 2

for i in range(- half,half + 1):

if i < 0:

print(' ' * (-i) + '*' * (half + i + 1))

elif i == 0:

print('*' * num)

else:

print(' ' * half + '*' * (half - i + 1))

19.猴子吃桃：

x = 1

for i in range(9):

x = (x + 1) * 2

print(x)