\n This problem is related to graphs, which often appear in coding tests, and it will focus on understanding friendships.
\n Friendships can be represented as ‘bidirectional edges’, and in this problem, we will implement an algorithm to output
\n the friends of a specific friend based on given friendships.\n<\/p>\n
\nProblem Description<\/strong>: There are N friends. Each friend considers each other a friend, and the friendships \nInput Format<\/strong>: \nOutput Format<\/strong>: \n To understand the problem, let’s think about how we can represent the given friendships. \n An ‘adjacency list’ is appropriate for representing friendships. \n Now, let’s implement the code in Swift to solve the problem. \n The code can be divided into three main parts. The explanations for each section are as follows.\n<\/p>\n \n Various input cases should be considered to test the written code. \n In this tutorial, we implemented an algorithm to understand friendships and output the \n We hope you continue to improve your skills by solving more problems.\n<\/p>\n <\/body><\/p>\n","protected":false},"excerpt":{"rendered":"
\n are given in pairs. Given these friendships, write a program that outputs the friend list of a specific friend.
\n However, duplicate friends should be excluded.\n<\/p>\n
\n – The first line contains two integers N (1 \u2264 N \u2264 100) and M (1 \u2264 M \u2264 1000).
\n – The next M lines consist of two integers A and B that represent the friendships.
\n – A and B are the numbers denoting friends, and A \u2260 B always holds.\n<\/p>\n
\n – Output the friend list of a specific friend K (1 \u2264 K \u2264 N) separated by spaces.\n<\/p>\nExample Input<\/h2>\n
\n5 5\n1 2\n1 3\n2 4\n3 4\n4 5\n3\n<\/pre>\n
Example Output<\/h2>\n
\n2 4\n<\/pre>\n
Problem Solving Process<\/h2>\n
Step 1: Understanding the Problem<\/h3>\n
\n Friendships can be represented as a graph, where ‘friends’ are ‘nodes’ and friendships are ‘edges’.
\n This allows us to easily find each friend’s friend list.\n<\/p>\nStep 2: Choosing a Data Structure<\/h3>\n
\n We can use a dictionary or an array to store each friend’s friend list.
\n In this problem, we will use an array with friend numbers as indices.\n<\/p>\nStep 3: Implementation<\/h3>\n
\n First, we will take the input and build an adjacency list to represent friendships, then write a program
\n that outputs the friend list of a specific friend K.\n<\/p>\n\nimport Foundation\n\nfunc main() {\n \/\/ Input\n let firstLine = readLine()!.split(separator: \" \").map { Int($0)! }\n let N = firstLine[0] \/\/ Number of friends\n let M = firstLine[1] \/\/ Number of friendships\n \n \/\/ Array to store friendships (adjacency list)\n var friends = [[Int]](repeating: [], count: N + 1)\n \n \/\/ Input friendships\n for _ in 0..Step 4: Code Explanation<\/h3>\n
\n
\n
\n
\n
Step 5: Testing the Code<\/h2>\n
\n For example, let's try the following test case:\n<\/p>\nExample Input 1<\/h3>\n
\n5 5\n1 2\n1 3\n2 4\n3 4\n4 5\n3\n<\/pre>\n
Example Output 1<\/h3>\n
\n2 4\n<\/pre>\n
Example Input 2<\/h3>\n
\n4 4\n1 2\n2 3\n3 4\n4 1\n1\n<\/pre>\n
Example Output 2<\/h3>\n
\n2 4\n<\/pre>\n
Example Input 3<\/h3>\n
\n4 4\n1 2\n3 4\n2 3\n1 4\n2\n<\/pre>\n
Example Output 3<\/h3>\n
\n1 3\n<\/pre>\n
Conclusion<\/h2>\n
\n friend list of a specific friend using Swift.
\n Graph problems have various applications, so it's essential to practice thoroughly to enhance
\n understanding of algorithms.\n<\/p>\n