Daily summary
review
This week's mind map
[the external chain picture transfer fails. The source station may have antitheft chain mechanism. It is recommended to save the picture and upload it directly (IMG eoqdofz31645362548051) (C: \ users \ ASUS \ pictures \ data analysis process \ unnamed file (11)] png)
Homework concern
# High order question: enter any positive integer and find out how many digits it is It's best to think of it as a loop while true and divide 10 to 0 print('') num=0 count=0 while True: num//=10 count+=1 if num==0: break print(count) # Judge whether the specified number is a prime number (prime number is a prime number, that is, a number that cannot be divided by other numbers except 1 and itself) *Use cycle forrange To take out every number,Re judgment:If it can be divided by other numbers in a certain range,Then it must not be on the prime side else Put it in break The front is because breakelse Caused by usage,Make sure you have break There is still content output after num=35 for x in range(2,num): if num%x==0: print('Not prime') break else: print('It's a prime') # Output 9 * 9 formula. Procedure analysis: Considering branches and columns, there are 9 rows and 9 columns in total, i control row and j control column. # print is indented in the first for, which means that the elements in the first group will be printed once, and the blank space will be printed once The first set of for is originally used to control rows for i in range(1,10): for j in range(1,i+1): result=i*j if result<10: print(i,'x',j,'=', result, ' ',end=' ',sep='') print(i,'x',j,'=', result, end=' ',sep='') print('')
new
1.while statement
After the principle meets the conditions, it will continue to make cyclic judgment until it meets the nonconforming conditions
while condition: Circulatory body Other statements # Use the while loop to print 'hello world!' five times a = 0 while a < 5: print('hello world!') a += 1 while and for Comparison of cycles # Enter an integer and print all even numbers between 0 and X x = int(input('integer:')) for i in range(0, x + 1, 2): print(i)
*Method to control the loop: the condition needs to be True at the beginning, False after n cycles, and end the loop. First define a variable with 0 (0 times), write the condition < several times, add 1 to it each time, and finally print (put the position into the loop body)
*Execution process: first judge the condition as
*Special circumstances: 1 If the condition is always True, it falls into an endless loop. To exit the loop, you can use the break function 2 If False at the beginning, it ends at the beginning
The rule of double circulation: when one layer of circulation takes out, the second layer of circulation will take out all
2. Circular keyword

Continue: end a loop (if you encounter continue when executing the loop body, when the loop ends, you can directly enter the next loop)

Break: when executing the loop body, if it encounters a break, it will not be recycled, and all results will be output only once And will not perform any other operations after break
# 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) while True: value=int(input('Please enter a(0100)Random number of:')) if value > num: print('Big') elif value < num: print('Small') else: print('You guessed right!fantastic!') break
3. About keyword else:
 The existence of else will not affect the execution of the original loop
 If the loop ends because it encounters a break, it will not be executed else exists to test break (understand)
str1 = '81283472' # Judge whether the string is a numeric string for x in str1: if not '0' <= x <= '9': print(str1, 'Not a pure numeric string') break else: print(str1, 'Is a pure numeric string')
4. Ternary operator
***grammar: Value 1 if expression else Value 2 #There is a definite value a=16 result=18 if a>17 else a print(result) # Example of expression with explicit value: if it is greater than 10, let a add 1, otherwise let a1 a=18 result=a+1 if a<10 else a1 print(result)
task
Basic questions
First week assignment
1, Multiple choice questions

Which of the following variable names is illegal? (C)
A. abc
B. Npc
C. 1name
D ab_cd

Which of the following options is not a keyword? (C)
A. and
B. print
C. True
D. in

Which of the following options corresponds to the correct code writing? (C)
A.
print('Python') print('Novice Village')
B.
print('Python') print('Novice Village')
C.
print('Python') print('Novice Village')
D.
print('Python''Novice Village')

Which of the following options can print 50? (B)
A.
print('100  50')
B.
print(100  50)

For quotation marks, what is the correct one to use in the following options? (D)
A.
print('hello)
B.
print("hello')
C.
print("hello")
D.
print("hello")
2, Programming problem

Write code and print good study, day, day up on the console!
print('good good study, day day up!') #result good good study, day day up!

Write code and print 5 times on the console you see see, one day!
for x in range(5): print('you see see, one day day!') # you see see, one day day! you see see, one day day! you see see, one day day! you see see, one day day! you see see, one day day!

Write code and print numbers 11, 12, 13,... 21
for x in range(11,22): print(x) # 11 12 13 14 15 16 17 18 19 20 21

Write code and print numbers 11, 13, 15, 17,... 99
for x in range(11,100): print(x) #

Write code and print numbers: 10, 9, 8, 7, 6, 5
for x in range(10,4,1): print(x) # 10 9 8 7 6 5

Write code and calculate: the sum of 1 + 2 + 3 + 4 +... + 20
sum=0 for x in range(21): sum+=x print(sum) # 210

Write code to calculate the sum of all even numbers within 100
result=0 for x in range(2,100,2): result+=x print(result) # 2450

Write code to count the number of numbers with 3 in 100 ~ 200
count=0 for x in range(103,193): if x%10==3: count+=1 print(count) # 9

Write code to calculate 2 * 3 * 4 * 5 ** 9 results
result=1 for x in range(2,10): result*=x print(result) # 362880

Enter a number. If the number entered is even, print even number; otherwise, print odd number
value=int(input('Enter a number:')) if value%2: print('Odd number') else: print('even numbers') # Enter a number:7 Odd number

Count the number of numbers within 1000 that can be divided by 3 but cannot be divided by 5.
count=0 for x in range(3,1000,3): if x%5!=0: count+=1 print(count) # 267
Higher order problem

Judge how many primes there are between 101200 and output all primes.
count=0 for x in range(101,199): if not x%2==0: count+=1 print(x) print(count) # 101 103 105 107 109 111 113 115 117 119 121 123 125 127 129 131 133 135 137 139 141 143 145 147 149 151 153 155 157 159 161 163 165 167 169 171 173 175 177 179 181 183 185 187 189 191 193 195 197 49

Find the cumulative value of integers 1 ~ 100, but it is required to skip all numbers with 3 bits.
sum=0 for x in range(1,101): if not x%10==3: sum+=x print(sum) # 4570

Write a program to calculate the factorial n of n! Results
n=10 for x in range(1,11): n*=x n+=n print(n) # 37158912000

Ask for 1 + 2+ 3!+…+ 20! And
sum=1 result=0 for x in range(1,21): sum*=x result+=sum print(result) # 2561327494111820313
A number with 3 bits.
sum=0 for x in range(1,101): if not x%10==3: sum+=x print(sum) # 4570

Write a program to calculate the factorial n of n! Results
n=10 for x in range(1,11): n*=x n+=n print(n) # 37158912000

Ask for 1 + 2+ 3!+…+ 20! And
sum=1 result=0 for x in range(1,21): sum*=x result+=sum print(result) # 2561327494111820313