Hello! In this session, we will cover the topic of set expressions, which frequently appear in coding tests using Kotlin<\/strong>. Through the problems I present, I will clarify the concept of sets and explain how sets can be utilized in Kotlin.<\/p>\n Here is the description of the problem:<\/p>\n When a set of integers is given, write a function that finds all subsets of that set and returns the number of unique sums of each subset. (The sum of subsets does not allow duplicates)<\/p>\n Input:<\/strong> A set of integers {a1, a2, …, an} (1 \u2264 n \u2264 20, 1 \u2264 a \u2264 100)<\/p>\n Output:<\/strong> The number of unique sums<\/p>\n<\/blockquote>\n Input: {1, 2, 3}<\/p>\n Output: 7<\/p>\n<\/blockquote>\n To understand this problem, one must first know the concepts of sets and subsets. A set is a collection of distinct objects where no duplicate objects are allowed. A subset is a set that includes some or all elements of the given set.<\/p>\n For example, all subsets of the set {1, 2, 3} are as follows:<\/p>\n To solve this, we need to find the sum of each of these subsets and count the unique values of these sums. However, it is important to note that we should not count duplicate sums.<\/p>\n We can use a recursive approach to create subsets. Since each element can either be included or not included, binary flags can be used. We construct subsets using combinations of indices.<\/p>\n Next, we calculate the sum of each created subset. To ensure that sums do not duplicate, we can use a Finally, we return the count of the stored sums.<\/p>\n Based on the above process, let’s write the code.<\/p>\n The above code works as follows:<\/p>\nProblem Description<\/h2>\n
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Input Example<\/h2>\n
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Problem Analysis<\/h2>\n
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Solution Process<\/h2>\n
Step 1: Creating Subsets<\/h3>\n
Step 2: Calculating the Sum of Subsets<\/h3>\n
HashSet<\/code>.<\/p>\nStep 3: Returning the Count of Unique Sums<\/h3>\n
Code Implementation<\/h2>\n
fun uniqueSubsetSums(nums: IntArray): Int {\n val sums = mutableSetOfCode Explanation<\/h3>\n