《Python程学设计基础》【第四章】习题

alb="abcdefghijklmnopqrstuvwxyz"
number="0123456789"
n1,n2,n3,n4=0,0,0,0        #n1、n2、n3分别统计数字、字母、空格和其它字符的个数
str=input("Enter your string:")
for c in str:
    if c in alb:
        n1+=1
    elif c in number:
        n2+=1
    elif c==' ':
        n3+=1
    else:
        n4+=1
print("The {}-character-string has:\n".format(len(str))
      +"{} letters\n".format(n1)
      +"{} numbers\n".format(n2)
      +"{} ' '\n".format(n3)
      +"{} other characters.".format(n4))

a=eval(input("Input the 1st number:"))
b=eval(input("Input the 2nd number:"))

div =1
for i in range(2,min(a,b)+1):
    if a%i==0 and b%i==0:
        div=i

mul=int(a*b/div)
print("For {} and {}:".format(a,b)+
      "the greatest common divisor is {}; ".format(div)+
      "the lowest common multiple is {}.".format(mul))

import random
x=random.randint(0,100)

while True:
    a=input("Enter a number you guess between 0 and 100:")
    try:
        if eval(a)>100 or eval(a)<0:
            print("Your number is out of range! Try again!")
            continue
        else:
            if eval(a)>x:
                print("Your number is too large, try again!")
                continue
            elif eval(a)<x:
                print("Your number is too low, try again!")
            else:
                print("Congratulation! Your number {} is correct!".format(x))
                break
    except TypeError:
        print("Wrong format!")
    except NameError:
        print("Wrong format!")

import random
a,b,c="car","goat1","goat2"       #a、b、c代表三扇门
sum=1000000                       #样本量

#不提前开门的情况：
win1=0
for i in range(sum):
    choice=random.choice([a,b,c])
    if choice=='car':
        win1+=1

print("The rate of winning on the 1st condition is {}".format(win1/sum))

#提前开门且改变选择的情况：
win2=0
for i in range(sum):
    choice=random.choice([a,b,c])
    if choice=='car':
        #prdoor=b/c
        choice=c                 #此时选b和c都一样

    elif choice=='goat1':
        #prdoor=c
        choice=a

    else:
        #prdoor=b
        choice=a

    if choice=='car':
        win2+=1
print("The rate of winning on the 2nd condition is {}".format(win2/sum))

输出结果：

The rate of winning on the 1st condition is 0.332045
The rate of winning on the 2nd condition is 0.667128