当前位置：网站首页>Day5: construct program logic

Day5: construct program logic

2022-07-24 11:51:00 【Sumarua】

Construct program logic

After learning the previous chapters , I think it is necessary to do some exercises here to consolidate what I have learned before , Although what we have learned so far is only Python The tip of the iceberg , But that's enough for us to build the logic in the program . For beginners of programming languages , In the study Python Core language elements of （ Variable 、 type 、 Operator 、 expression 、 Branching structure 、 Circulation structure, etc ） after , One of the things that must be done is to try to use what we have learned to solve real problems , In other words, it is to exercise the algorithm described in human natural language （ Methods and steps to solve the problem ） Translate into Python The power of code , And this has to be done through a lot of practice .

In this chapter, we have sorted out some classic cases and exercises for you , I hope that through these examples , On the one hand, it helps us consolidate what we have learned before Python knowledge , On the other hand, it helps us understand how to establish the logic in the program and how to use some simple algorithms to solve real problems .

Classic example

seek Narcissistic number .
explain ： Narcissus number is also called super perfect number invariant 、 Narcissistic number 、 Self idempotent 、 Armstrong number , It's a 3 digit , The sum of the cubes of each digit of the number is exactly equal to itself , for example ： $1^3 + 5^3+ 3^3=153$ .
```
"""
 Find out the number of all daffodils 

"""

for num in range(100, 1000):
    low = num % 10
    mid = num // 10 % 10
    high = num // 100
    if num == low ** 3 + mid ** 3 + high ** 3:
        print(num)
```
In the code above , We find out the single digit of a three digit number by integer division and modulo operation 、 Ten and a hundred , This little technique is still commonly used in actual development . In a similar way , We can also reverse a positive integer , for example ： take 12345 become 54321, The code is as follows .
```
"""
 The inverse of a positive integer 

"""

num = int(input('num = '))
reversed_num = 0
while num > 0:
    reversed_num = reversed_num * 10 + num % 10
    num //= 10
print(reversed_num)
```
A hundred money and a hundred chickens problem .
explain ： A hundred money and a hundred chickens are ancient mathematicians in China Qiu Jian Zhang stay 《 Sutra 》 A mathematical problem raised in a book ： A chicken is worth five , A hen is worth three , A chicken is worth three . A hundred dollars for a hundred chickens , Ask jiweng 、 Hen 、 Every chicken has its own geometry ？ The translation into modern Chinese is ： cock 5 One yuan , hen 3 One yuan , Chick 1 Three yuan , use 100 A hundred chickens for $1 , Ask the rooster 、 hen 、 How many chickens are there each ？
```
"""
《 A hundred money and a hundred chickens 》 problem 

"""

for x in range(0, 20):
    for y in range(0, 33):
        z = 100 - x - y
        if 5 * x + 3 * y + z / 3 == 100:
            print(' cock : %d only ,  hen : %d only ,  Chick : %d only ' % (x, y, z))
```
The method used above is called Exhaustive method , Also known as Violent search , This method enumerates all possible candidates of alternative solutions one by one and checks whether each candidate conforms to the description of the problem , Finally, the solution of the problem is obtained . This method looks clumsy , But for computers with very powerful computing power , It is usually a feasible or even good choice , And if the solution of the problem exists , This method must be able to find it .

CRAPS Gambling games .

explain ：CRAPS Also known as Citi dice , It is a very popular table gambling game in Las Vegas . The game uses two dice , Players get points by rolling two dice to play the game . The simple rule is ： If the player shakes the dice for the first time 7 Point or 11 spot , Players win ; If the player shakes out for the first time 2 spot 、3 Point or 12 spot , Chuang Jiasheng ; Other players continue to roll dice , If the player shakes out 7 spot , Chuang Jiasheng ; If the player shakes the points for the first time , Players win ; Other points , Players continue to want dice , Until the winner is decided .

"""
Craps Gambling games 
 We set the player to start the game with 1000 A bet of $ 
 The condition for the end of the game is that the player loses all his bets 

"""
from random import randint

money = 1000
while money > 0:
    print(' Your total assets are :', money)
    needs_go_on = False
    while True:
        debt = int(input(' Please bet : '))
        if 0 < debt <= money:
            break
    first = randint(1, 6) + randint(1, 6)
    print(' The player shakes out %d spot ' % first)
    if first == 7 or first == 11:
        print(' Players win !')
        money += debt
    elif first == 2 or first == 3 or first == 12:
        print(' Chuang Jiasheng !')
        money -= debt
    else:
        needs_go_on = True
    while needs_go_on:
        needs_go_on = False
        current = randint(1, 6) + randint(1, 6)
        print(' The player shakes out %d spot ' % current)
        if current == 7:
            print(' Chuang Jiasheng ')
            money -= debt
        elif current == first:
            print(' Players win ')
            money += debt
        else:
            needs_go_on = True
print(' You're broke ,  Game over !')

### Useful exercises

Generate Fibonacci sequence Before 20 Number .
explain ： Fibonacci sequence （Fibonacci sequence）, Also called golden section series , It's Leonardo, an Italian mathematician · Fibonacci （Leonardoda Fibonacci） stay 《 Book of calculation 》 In this paper, we propose a series of numbers for the growth rate of rabbit under ideal hypothesis , So this sequence is also called " Rabbit Series ". The characteristic of Fibonacci series is that the first two numbers of the series are 1, Start with the third number , Each number is the sum of its first two numbers , Form like ：1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, …. Fibonacci series in modern physics 、 Quasicrystal structure 、 There are direct applications in chemistry and other fields .
find 10000 Inside Perfect number .
explain ： Perfect number is also called complete number or complete number , All its true factors （ I.e. factors other than themselves ） And （ Factor function ） Exactly equal to itself . for example ：6（ $6 = 1 + 2 + 3$ ） and 28（ $28 = 1 + 2 + 4 + 7 + 14$ ） It's the perfect number . Perfect numbers have many magical properties , If you are interested, you can learn .
Output 100 All prime numbers within .
explain ： Prime numbers mean that only 1 A positive integer divided by itself （ barring 1）.