1. Introduction
Coding tests are currently an important part of the hiring process for many companies.
However, countless technical questions and algorithm problems are tormenting the applicants.
In this article, we will present algorithm problems that will help prepare for coding tests using Java,
and emphasize the importance of debugging during the problem-solving process.
2. Algorithm Problem
Problem Description
Write a function that returns the indices of two numbers from a given integer array
such that their sum equals a specific value.
Each element in the array is unique, and the returned indices start from 0.
Input
- The first line contains an integer array nums.
- The second line contains an integer target.
Output
You should return an array containing the indices of the two numbers that sum to the target.
Example
Input: nums = [2, 7, 11, 15], target = 9
Output: [0, 1]
(2 + 7 = 9)
3. Problem Solving Process
3.1 Algorithm Design
To solve this problem, we need to search each element while checking if the complement exists in the array.
We can use a hashmap to achieve this,
allowing us to solve the problem with a time complexity of O(n).
Understanding hashmaps is the first step to solving this problem.
3.2 Java Code Implementation
import java.util.HashMap;
public class Solution {
public int[] twoSum(int[] nums, int target) {
HashMap map = new HashMap<>();
for (int i = 0; i < nums.length; i++) {
int complement = target - nums[i];
if (map.containsKey(complement)) {
return new int[] { map.get(complement), i };
}
map.put(nums[i], i);
}
throw new IllegalArgumentException("No two sum solution");
}
}
4. Importance of Debugging
While preparing for coding tests,
debugging is as important as implementing the algorithm logic.
First, we need to verify that the written code functions as intended.
The ability to quickly identify and fix bugs or errors is essential for a developer.
Nonetheless, things may not go smoothly at first,
so you can try the following debugging techniques.
- Check for syntax and logical errors line by line: It is useful to analyze code line by line
or print each variable. - Write unit tests: Create tests to validate whether a specific function works correctly,
helping to discover errors. - Utilize debugging tools in the IDE: Use the debugger feature provided by the IDE
to execute the code step by step.
5. Conclusion
The process of solving algorithm problems is more than just finding the answers.
Problem-solving skills, code implementation skills, and debugging skills should develop together.
We hope you prepare better for coding tests through programming languages like Java,
while also strengthening your debugging skills.