Think like computer scientists Python (3)

Fifth chapter conditions and recursion

"//" represents the down-divide method

"%" modulo operator

The code that determines the intertextuality:

#-*-Coding: UTF-8-*-

def First (word):

return word[0]

def Last (word):

return Word[-1]

def Middle(word):

return Word[1:-1]

def Huwen(word):

If Len (word) <=1:

Return True

If first (word)!=last (word):

Return False

Else

Return Huwen (middle (word))

Print (Huwen (' a '))

Print (Huwen ('afbhj'))

Print (Huwen ('adhsuia'))

Print (Huwen ('heeh'))

def Huwen(WORD1,WORD2):

If Len (word1)! = Len (word2):

Return False

I=0

J=len (WORD2)-1

While j>0:

If WORD1[I]!=WORD2[J]:

Return False

I+=1

J-=1

Return True

Print (Huwen ('hkl', 'lkh'))

def Is_huwen(word):

I=0

J=len (Word)-1

While I<=j:

If WORD[I]!=WORD[J]:

Return False

I+=1

J-=1

Return True

Print (Is_huwen ('guug'))

epsilon=0.0000001

Write the following code in Python

#-*-Coding:utf-8-*-

Import Math

def Jiecheng(n):

If n==0:

Return 1

Else

b=jiecheng (n-1)

C=n*jiecheng (n-1)

Return C

def Estimatepi():

D= (2*MATH.SQRT (2))/9801

K=0

Total=0

While True:

E= (Jiecheng (4*k)) * (1103+26390*k)

F= (Jiecheng (k)) **4

g=f* (396** (4*k))

Total1=d*e/g

Total+=total1

If ABS (TOTAL1) <1e-15:

Break

K+=1

Return 1/total

Print (Estimatepi ())

Two methods for traversing strings

Find usage

#-*-Coding: UTF-8-*-

word=' banana '

Print (Word.find ('na')) #2 look for the subscript when a string is encountered for the first time

Print (Word.find ('na', 3)) #4 indicates which subscript to start looking for

Print (Word.find (' A ', 0, 1)) #-1 indicates from which small label to start finding which of the following table ends

Find a word with three repeating letters

#-*-Coding:utf-8-*-

def Liayiyang(word):

Count=0

I=0

While I<len (word)-1:

If WORD[I]==WORD[I+1]:

Count+=1

If count==3:

Return True

I=i+2

Else

Count=0

I=i+1

Return False

def Wenjian():

Fin = open (' c:\\users\\chenxi\\Desktop\\words.txt ')

For line in Fin:

Word=line.strip ()

If Liayiyang (word):

Print (word)

Wenjian ()

Think like computer scientists Python (3)