search
HomeBackend DevelopmentPython TutorialPython implements finding the longest non-repeating substring for a given string

This article mainly introduces Python's method of finding the longest non-repeating substring for a given string, involving Python's traversal, sorting, calculation and other related operation skills for strings. Friends who need it can refer to it

The example in this article describes Python's method of finding the longest non-repeating substring for a given string. Share it with everyone for your reference, the details are as follows:

Question:

Given a string, find the longest repeating subsequence in it , if the string is composed of a single character, such as "aaaaaaaaaaaaa", then the output that meets the requirements is a

Thinking:

There are two ideas here The first thing I can think of is

(1) Traverse the string from the beginning, set the flag bit, and when you find that it coincides with the previous flag bit in the process of going back, go back and check the new substring. Whether the string is the same as the previous string or the substring of the previous string, if it is the same, the substring is recorded and the count is increased by 1 until the processing is completed

(2) Use the sliding window slicing mechanism to generate all slice connections For statistics and processing, the function of double sorting is mainly used.

This article uses the second method. The following is the specific implementation:


#!usr/bin/env python
#encoding:utf-8
'''''
__Author__:沂水寒城
功能:给定一个字符串,寻找最长重复子串
'''
from collections import Counter
def slice_window(one_str,w=1):
  '''''
  滑窗函数
  '''
  res_list=[]
  for i in range(0,len(one_str)-w+1):
    res_list.append(one_str[i:i+w])
  return res_list
def main_func(one_str):
  '''''
  主函数
  '''
  all_sub=[]
  for i in range(1,len(one_str)):
    all_sub+=slice_window(one_str,i)
  res_dict={}
  #print Counter(all_sub)
  threshold=Counter(all_sub).most_common(1)[0][1]
  slice_w=Counter(all_sub).most_common(1)[0][0]
  for one in all_sub:
    if one in res_dict:
      res_dict[one]+=1
    else:
      res_dict[one]=1
  sorted_list=sorted(res_dict.items(), key=lambda e:e[1], reverse=True)
  tmp_list=[one for one in sorted_list if one[1]>=threshold]
  tmp_list.sort(lambda x,y:cmp(len(x[0]),len(y[0])),reverse=True)
  #print tmp_list
  print tmp_list[0][0]
if __name__ == '__main__':
  print "脚本之家测试结果:"
  one_str='abcabcd'
  two_str='abcabcabd'
  three_str='bbbbbbb'
  main_func(one_str)
  main_func(two_str)
  main_func(three_str)


The results are as follows:


Related recommendations:

Python implementation follows Specify the requirement to output a number in reverse order

Python implements the method of inputting multiple lines in IDLE


The above is the detailed content of Python implements finding the longest non-repeating substring for a given string. For more information, please follow other related articles on the PHP Chinese website!

Statement
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
What are the alternatives to concatenate two lists in Python?What are the alternatives to concatenate two lists in Python?May 09, 2025 am 12:16 AM

There are many methods to connect two lists in Python: 1. Use operators, which are simple but inefficient in large lists; 2. Use extend method, which is efficient but will modify the original list; 3. Use the = operator, which is both efficient and readable; 4. Use itertools.chain function, which is memory efficient but requires additional import; 5. Use list parsing, which is elegant but may be too complex. The selection method should be based on the code context and requirements.

Python: Efficient Ways to Merge Two ListsPython: Efficient Ways to Merge Two ListsMay 09, 2025 am 12:15 AM

There are many ways to merge Python lists: 1. Use operators, which are simple but not memory efficient for large lists; 2. Use extend method, which is efficient but will modify the original list; 3. Use itertools.chain, which is suitable for large data sets; 4. Use * operator, merge small to medium-sized lists in one line of code; 5. Use numpy.concatenate, which is suitable for large data sets and scenarios with high performance requirements; 6. Use append method, which is suitable for small lists but is inefficient. When selecting a method, you need to consider the list size and application scenarios.

Compiled vs Interpreted Languages: pros and consCompiled vs Interpreted Languages: pros and consMay 09, 2025 am 12:06 AM

Compiledlanguagesofferspeedandsecurity,whileinterpretedlanguagesprovideeaseofuseandportability.1)CompiledlanguageslikeC arefasterandsecurebuthavelongerdevelopmentcyclesandplatformdependency.2)InterpretedlanguageslikePythonareeasiertouseandmoreportab

Python: For and While Loops, the most complete guidePython: For and While Loops, the most complete guideMay 09, 2025 am 12:05 AM

In Python, a for loop is used to traverse iterable objects, and a while loop is used to perform operations repeatedly when the condition is satisfied. 1) For loop example: traverse the list and print the elements. 2) While loop example: guess the number game until you guess it right. Mastering cycle principles and optimization techniques can improve code efficiency and reliability.

Python concatenate lists into a stringPython concatenate lists into a stringMay 09, 2025 am 12:02 AM

To concatenate a list into a string, using the join() method in Python is the best choice. 1) Use the join() method to concatenate the list elements into a string, such as ''.join(my_list). 2) For a list containing numbers, convert map(str, numbers) into a string before concatenating. 3) You can use generator expressions for complex formatting, such as ','.join(f'({fruit})'forfruitinfruits). 4) When processing mixed data types, use map(str, mixed_list) to ensure that all elements can be converted into strings. 5) For large lists, use ''.join(large_li

Python's Hybrid Approach: Compilation and Interpretation CombinedPython's Hybrid Approach: Compilation and Interpretation CombinedMay 08, 2025 am 12:16 AM

Pythonusesahybridapproach,combiningcompilationtobytecodeandinterpretation.1)Codeiscompiledtoplatform-independentbytecode.2)BytecodeisinterpretedbythePythonVirtualMachine,enhancingefficiencyandportability.

Learn the Differences Between Python's 'for' and 'while' LoopsLearn the Differences Between Python's 'for' and 'while' LoopsMay 08, 2025 am 12:11 AM

ThekeydifferencesbetweenPython's"for"and"while"loopsare:1)"For"loopsareidealforiteratingoversequencesorknowniterations,while2)"while"loopsarebetterforcontinuinguntilaconditionismetwithoutpredefinediterations.Un

Python concatenate lists with duplicatesPython concatenate lists with duplicatesMay 08, 2025 am 12:09 AM

In Python, you can connect lists and manage duplicate elements through a variety of methods: 1) Use operators or extend() to retain all duplicate elements; 2) Convert to sets and then return to lists to remove all duplicate elements, but the original order will be lost; 3) Use loops or list comprehensions to combine sets to remove duplicate elements and maintain the original order.

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

Dreamweaver Mac version

Dreamweaver Mac version

Visual web development tools

SAP NetWeaver Server Adapter for Eclipse

SAP NetWeaver Server Adapter for Eclipse

Integrate Eclipse with SAP NetWeaver application server.

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

MantisBT

MantisBT

Mantis is an easy-to-deploy web-based defect tracking tool designed to aid in product defect tracking. It requires PHP, MySQL and a web server. Check out our demo and hosting services.

DVWA

DVWA

Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software