How to improve the problem-solving ability of Leetcode?

How to improve the problem-solving ability of Leetcode?

Leetcode is an online programming platform that provides a variety of algorithm and data structure topics, allowing programmers to practice and improve their programming skills. Many people use Leetcode as a learning and interview tool, hoping to master more knowledge and skills by brushing the questions.

However, brushing the questions is not an easy task. Sometimes, we may encounter such a predicament: we have consciously learned a lot of knowledge, but when we actually start to do the questions, there is still the problem of "one pen, one pair of hands, one Leetcode for one night" Dilemma. Have you ever had such an experience, the question type is not too difficult, and you can figure it out by reading the solution, but when you do it yourself, you look at the question face to face and have no way to start.

Is this dilemma bothering you now or has it been overcome by you? If you are still struggling, then this blog may help you. I will share some methods and techniques that I have summed up in the process of brushing the questions, hoping to help you improve Leetcode's problem-solving ability.

1. Understand the topic

First of all, what we have to do is to understand the topic. This may sound simple, but it's actually a step that many people ignore. Sometimes, we may be confused by some details or traps in the topic, causing us to fail to grasp the essence and requirements of the topic. Sometimes, we may not be familiar with some concepts or terms in the topic, which makes us unable to accurately understand the meaning of the topic.

Therefore, before starting to do the questions, we must read the questions carefully and grasp the following aspects:

• What are the inputs and outputs of the topic? The data type, range, format, etc. of the input and output must be clear.
• What are the constraints of the topic? Time complexity, space complexity, boundary conditions, etc. must be considered.
• What is an example of a topic? Examples can help us understand the intent and logic of the topic.
• What is the difficulty of the topic? The difficulty may be a special situation, an implicit rule, an optimization method, etc.

After understanding the topic, we can try to describe the topic in our own words, or use pseudocode to express the algorithm idea. This can help us check whether we really understand the topic and prepare for subsequent coding.

2. Analysis ideas

Second, what we have to do is to analyze the train of thought. This step is the most important and difficult step in the process of brushing the questions. Because different problems may have different solutions, and different solutions may have different advantages and disadvantages. We need to choose an appropriate solution based on our own knowledge and experience, or combine multiple solutions to solve the problem.

The process of analyzing ideas can be divided into the following steps:

• Find the essence of the problem. We need to abstract the topic and find its essence, that is, the knowledge points of the algorithms and data structures it involves. For example, if the topic is about arrays, we have to think about the characteristics and operations of arrays; if the topic is about linked lists, we have to think about the characteristics and operations of linked lists; if the topic is about trees, we have to think about the characteristics of trees and operations; and so on.
• Look for patterns in the problem. We need to look for some laws or patterns from the topic, which may be given by the topic itself, or discovered by ourselves. For example, if the topic is about sorting, we have to think of the method and principle of sorting; if the topic is about dynamic programming, we have to think of state transition equations and boundary conditions; if the topic is about backtracking, we have to think of recursion and pruning; and so on.
• Solutions to design problems. We need to design one or more solutions to solve the problem according to the nature and laws of the problem. When designing a solution, we have to consider the following aspects:
  • Is the solution correct? We want to ensure that the solution correctly handles all possible inputs and outputs, both normal and abnormal.
  • Is the solution efficient? We should try to optimize the time complexity and space complexity of the solution so that it meets the constraints of the topic.
  • Is the solution concise? We want to simplify the logic and code of the solution as much as possible to make it easy to understand and implement.

After analyzing the ideas, we can describe the solution with words or diagrams, or implement the solution with pseudocode or real code. This can help us verify our ideas and prepare for subsequent tests.

3. Write the code

Next, all we have to do is write the code. This step is the most intuitive and practical step in the process of brushing the questions. Because in the end we have to use code to implement our ideas, and use code to pass the test cases of Leetcode.

The process of writing code can be divided into the following steps:

• Choose the appropriate language. We have to choose an appropriate programming language to implement the solution according to our own preferences and habits. Different languages ​​may have different strengths and weaknesses such as syntax, functionality, performance, etc. We need to be familiar with the language of our choice and follow its norms and styles.
• Realize basic functions. We need to use the code to realize the basic functions according to the solution designed by ourselves. When implementing basic functions, we should pay attention to the following aspects:
  • Is the code correct? We need to ensure that the code can be executed correctly and conform to the input and output formats of the title.
  • Is the code efficient? We want to make sure that the code runs in a reasonable amount of time without taking up too much memory space.
  • Is the code concise? We need to ensure that there are no redundant or redundant parts of the code, and that the structure is clear, the variable names are reasonable, and the comments are sufficient.
• Debug errors and exceptions. We need to use the test cases provided by Leetcode or the test cases designed by ourselves to check whether the code has errors or exceptions. Errors or exceptions may be syntax errors, logic errors, boundary errors, etc. When debugging errors and exceptions, we should pay attention to the following aspects:
• Locating errors and exceptions. We need to use debugging tools or print statements to find the location and cause of errors or exceptions.
• Fix bugs and exceptions. We need to modify the code according to the type and cause of the error or exception so that it can run correctly.
• Validation errors and exceptions. We have to use test cases again to verify that the code has fixed bugs or exceptions and has not introduced new bugs or exceptions.

After writing the code, we can submit the code to Leetcode to see if we can pass all the test cases, and check the performance and ranking of our code. This can help us evaluate our code and prepare for subsequent optimization.

4. Optimization ideas

Finally, what we have to do is to optimize the thinking. This step is the most challenging and rewarding step in the process of brushing the questions. Because optimization ideas allow us to deeply understand and master problems and solutions from different angles and levels.

The process of optimizing ideas can be divided into the following steps:

• Compare different solutions. We need to compare the solutions designed or implemented by ourselves with those designed or implemented by others to see the similarities and differences, advantages and disadvantages, applicable scenarios, etc. between them. When comparing different solutions, we should pay attention to the following aspects:
  • Is the solution correct? We want to ensure that the solution correctly handles all possible inputs and outputs, both normal and abnormal.
  • Is the solution efficient? We want to compare the time complexity and space complexity of the solution to see which solution saves more time and space.
  • Is the solution concise? We will compare the logic and code of the solution to see which solution is easier to understand and implement.
• Learn other knowledge points. We need to learn other related or expanded knowledge points based on the knowledge points involved in the topic and solution. When learning other knowledge points, we should pay attention to the following aspects:
  • Are knowledge points important? We need to judge whether knowledge points are of great significance to the learning of algorithms and data structures, or have practical value for solving practical problems.
  • Is the knowledge point in-depth? We must master the principles and details of knowledge points, and be able to use knowledge points to analyze and solve problems.
  • Is the knowledge point extensive? We need to understand the application and changes of knowledge points in different fields or scenarios, and be able to flexibly adjust and improve knowledge points.
• Summarize your own experience. We have to summarize our experience and lessons based on the problems and gains we encountered in the process of brushing the questions. When summarizing our experience, we should pay attention to the following aspects:
  • Does experience work? We want to verify whether the experience we have summed up can help us improve Leetcode's problem-solving ability, and is applicable to other similar or different problems.
  • Is the experience universal? We need to abstract the experience we have summed up and summarize it into some general methods or techniques so that it can be applied to more problems and scenarios.
  • Is the experience updated? We must constantly update our summed up experience, and communicate and share with others, so that it can keep up with the development and changes of the times.

After optimizing our thinking, we can use blogs or notes to record our thinking and experience, or use videos or speeches to show our thinking and experience. This can help you consolidate and review knowledge, and prepare for subsequent learning and progress.

Summarize

Scratching questions is a great way to learn and improve your programming skills, but it's also a hard way. We need to have certain methods and skills in order to effectively brush the questions. This article shares the four steps I summed up in the process of brushing the questions: understanding the topic, analyzing ideas, writing code, and optimizing ideas. Hope to be of help to you. If you have other methods or techniques, please leave a message in the comment area. Thanks!