Summary of while loop of ternary operator
1, Ternary operator
Ternary operator of python
 Syntax:
Value 1 if expression else Value 2
 Operation rule: if the result of the expression is True, the result of the whole operation is the value 1, otherwise it is the value 2
# Case: if a is greater than 10, let a add 1, otherwise let a subtract 1 (use the trinomial operator) a = 18 result = a + 1 if a > 10 else a  1 print(result)
2, while loop
1.while loop
 Syntax:
while Conditional statement: Circulatory body
 explain:
while  keyword; Fixed writing
Conditional statement  can be any resulting expression (assignment statement)
:  Fixed writing
Loop body  one or more statements that maintain an indent with while; The loop body is the code that will be executed repeatedly by flash
 Execution process
First judge whether the conditional statement is True. If so, execute the loop body; After executing the loop body, judge whether the conditional statement is True. If so, execute the loop body again... And so on. If the conditional statement is false, the loop ends.
#Case 1: use while to print hello word five times! n = 0 while n < 5: n += 1 print('hello word!')
#Case 2: enter the login password until it is entered correctly password = '123456' value = input('Please input a password:') while value != password: value = input('Please input a password:') print('Login successful!')
2. Selection of for and while
If the number of cycles is determined, use the for loop; If the number of cycles is uncertain, use while
(use for for all problems that can be solved with for, and use while only for those that cannot be solved)
3, Circular keyword
1.continue and break
 continue
Function: end a cycle (if continue is encountered when executing the cycle body, when the cycle ends, directly enter the next cycle)
#Case 1: printing three rows of aaa for x in range(3): print('aaa') continue print('bbb')
#Case 2: printing odd numbers within 099 for x in range(100): if x % 2 == 0: continue print(x)
 break
Function: end the whole loop (if you encounter a break when executing the loop body, the whole loop will end directly)
#Case 1: print a row of aaa for x in range(3): print('aaa') break print('bbb')
while encountering break:
while True: Actions that need to be repeated if Conditions for the end of the cycle: break
#Case: randomly generate a random number from 0 to 100. The player inputs the number. The input number is equal to the generated number. The game is over! If it is not equal, give a prompt of 'big' or 'small' from random import randint num = randint(0,100) c = 0 while True: n = int(input('Please enter a number:')) c += 1 if n > num: print('Big!') elif n < num: print('Small!') else: break print('Congratulations, you guessed right!Guess together',c,'second')
4, else keyword
1. Complete cycle structure
 Complete for:
for variable in Sequence: Circulatory body else: Code snippet
 Complete while:
while Conditional statement: Circulatory body else: Code snippet
 About else:
 The existence of else will not affect the execution of the original loop
 The code after else will be executed after the end of the loop (if the loop ends because of a break, it will not be executed)
#Case: judge whether the string is a pure number str = '3465475' for x in str: if not '0' <= x <= '9': print(str, 'Not a pure numeric string') break else: print(str, 'Is a pure numeric string')
task

Judge how many primes there are between 101200 and output all primes.
count = 0 for i in range(100, 201): for j in range(2,i1): if i % j == 0: break else: count += 1 print(i) print(count)

Find the cumulative value of integers 1 ~ 100, but it is required to skip all numbers with 3 bits.
sum = 0 for i in range(1,101): if i % 10 != 3: sum += i print(sum)

There is a sequence of fractions: 2 / 1, 3 / 2, 5 / 3, 8 / 5, 13 / 8, 21 / 13... Find the 20th fraction of this sequence
a = 2 b = 1 for i in range(20): a,b = a + b,a print(a,'/',b)

Write a program to calculate the factorial n of n! Results
n = int(input('Please enter an integer:')) num = 1 for i in range(1,n + 1): num *= i print(num)

Ask for 1 + 2+ 3!+…+ 20! And
num = 1 sum = 0 for i in range(1,21): num *= i sum +=num print(sum)

Write a program to find the result of the expression a + aa + aaa + aaaa +... Where a is a number from 1 to 9, and the number of summation items is controlled by n. (A and N can be expressed as variables)
For example: when a is 3 and n is 5: 3 + 33 + 333 + 3333 + 33333
a = int(input('Please enter a Value of:')) n = int(input('Please enter n Value of:')) sum = 0 m = a for i in range(1,n+1): sum += a a = a * 10 + m print(sum)

Console output triangle
a.according to n The corresponding shape is output according to the different values of n = 5 Time n = 4 ***** **** **** *** *** ** ** * * n = int(input('Please enter an integer:')) for i in range(n,0,1): print('*' * n) n = 1 b.according to n The corresponding shape is output according to the different values of(n Odd number) n = 5 n = 7 * * *** *** ***** ***** ******* n = int(input('Please enter an odd number:')) for i in range(1,n + 1,2): m = int((n  i)/ 2 ) print(' ' * m,'*' * i) c. according to n The corresponding shape is output according to the different values of n = 4 1 121 12321 1234321 n = 5 1 121 12321 1234321 123454321 n = int(input('Please enter an integer:')) c = n for i in range(1, n + 1): for l in range(1, n  i + 1): print(' ',end='') for j in range(1,i + 1): print(j,end='') for k in range(j  1, 0, 1): print(k, end='') print('')

Xiaoming's unit issued a 100 yuan shopping card. Xiaoming went to the supermarket to buy three kinds of washing and chemical products, shampoo (15 yuan), soap (2 yuan) and toothbrush (5 yuan). If you want to spend 100 yuan exactly, what combination of purchase can you have?
for a in range(7): for b in range(21): for c in range(51): if 15 * a + 5 * b + 2 * c == 100: print(a,b,c)

The thickness of a piece of paper is about 0.08mm. How many times can it be folded in half to reach the height of Mount Everest (8848.13m)?
n = 1 while True: n += 1 if 0.08 * 0.001 * 2 ** n >= 8848.13: print(n) break

Classical question: a pair of rabbits give birth to a pair of rabbits every month from the third month after birth. The little rabbit grows to another pair of rabbits every month after the third month. If the rabbits don't die, what is the total number of rabbits every month?
a = b = 1 c = 0 n = int(input('Please enter the month:')) if n == 1 or n == 2: print('1') else: i = 2 while i < n: c = a + b a = b b = c i += 1 print(c)

Decompose a positive integer into prime factors. For example: enter 90 and print out 90=2x3x3x5.
a = int(input('Please enter a positive integer:')) i = 2 num = a print(a, '=', end='',sep='') while True: if num % i == 0: num = num // i print(i,'x',end='',sep='') i = 1 if num // 2 == i: print(num) break i += 1

A company uses a public telephone to transmit data. The data is a four digit integer and is encrypted in the transmission process. The encryption rules are as follows: add 5 to each number, then replace the number with the remainder of sum divided by 10, and then exchange the first and fourth bits, and the second and third bits. Find the encrypted value of the input four digit integer
num = int(input('Please enter a four digit integer:')) ge = (num % 10 + 5) % 10 shi = (num // 10 % 10 + 5) % 10 bai = (num // 100 % 10 + 5) % 10 qian = (num // 1000 + 5) % 10 print(qian,bai,shi,ge)

Decompose a positive integer into prime factors. For example: enter 90 and print out 90=2x3x3x5.
a = int(input('Please enter a positive integer:')) i = 2 num = a print(a, '=', end='',sep='') while True: if num % i == 0: num = num // i print(i,'x',end='',sep='') i = 1 if num // 2 == i: print(num) break i += 1

The principal of 10000 yuan is deposited in the bank with an annual interest rate of 3%. Every one year, add the principal and interest as the new principal. Calculate the principal obtained after 5 years.
sum = 0 a = 10000 for i in range(1,6): b = a * (1 + 0.003) ** i sum += b print(sum)

Enter an integer and calculate the sum of its digits. (Note: the input integer can be any bit)
sum = 0 m = 1 a = 1 n = int(input('Please enter an integer:')) for i in range(1,n + 1): a = n // 10 ** (m  1) % 10 m += 1 sum += a print(sum)

Find the maximum common divisor and minimum common multiple of two numbers. (hint: the common divisor must be less than or equal to the smaller of the two numbers, and can be divided by the two numbers at the same time; the common multiple must be greater than or equal to the larger of the two numbers, and the multiple of the larger number can be divided by the decimal of the two numbers)
m = int(input('Please enter m Value of:')) n = int(input('Please enter n Value of:')) min = m if n > m else n for i in range(2,n * m + 1): if i % m == 0 and i % n == 0: break for x in range(1,min + 1): if m % x == 0 and n % x == 0: a = x print('Least common multiple:',i) print('Maximum common factor:',a)