{"id":33866,"date":"2024-11-01T09:21:24","date_gmt":"2024-11-01T09:21:24","guid":{"rendered":"http:\/\/atmokpo.com\/w\/?p=33866"},"modified":"2024-11-01T10:55:30","modified_gmt":"2024-11-01T10:55:30","slug":"c-coding-test-course-hacking-efficiently","status":"publish","type":"post","link":"https:\/\/atmokpo.com\/w\/33866\/","title":{"rendered":"C# Coding Test Course, Hacking Efficiently"},"content":{"rendered":"

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Coding tests are an essential process that many software developers and engineers must undergo to pass the entry barrier. In this article, we will discuss how to solve algorithm problems commonly encountered in coding tests using C#. In particular, we will explore what an efficient hacking process is and the algorithm patterns required for it.<\/p>\n

Problem: Sum of Two Numbers<\/h2>\n

Given an integer array and a target integer ‘target’, find the indices of the two numbers in the array that add up to the ‘target’. The indices start from 0, and each number must be used exactly once.<\/p>\n

Example Input<\/h3>\n
nums = [2, 7, 11, 15]\ntarget = 9<\/pre>\n
Example Output<\/h3>\n
[0, 1]<\/pre>\n
Problem Interpretation<\/h3>\n
The above problem is quite famous as the ‘Two Sum’ problem. You must choose two numbers from the given array such that their sum equals the provided target value. This problem can be approached in various ways, but here we will focus on an efficient approach.<\/p>\n
Approach<\/h3>\n
1. **Brute Force**: This method checks all possible pairs in the array to see if their sum matches the ‘target’. However, this approach has a time complexity of O(n^2), making it very inefficient.<\/p>\n
2. **Using a HashMap**: This method uses a hashmap in the form of a dictionary to store the complement of the current number (target – current number) that we are currently looking at. This approach can solve the problem with a time complexity of O(n).<\/p>\n
Implementation<\/h3>\n
C# Code Implementation<\/h4>\n
\nusing System;\nusing System.Collections.Generic;\n\npublic class Solution\n{\n    public int[] TwoSum(int[] nums, int target)\n    {\n        Dictionary map = new Dictionary();\n\n        for (int i = 0; i < nums.Length; i++)\n        {\n            int complement = target - nums[i];\n            if (map.ContainsKey(complement))\n            {\n                return new int[] { map[complement], i };\n            }\n            map[nums[i]] = i;\n        }\n        throw new ArgumentException(\"No two sum solution\");\n    }\n}\n    <\/pre>\n
Code Explanation<\/h3>\n