LeetCode 567 Permutation in String

コミュカレでイントロ Java の授業を取っていてだされた宿題に LeetCode 567 Permutation in String に近いものがあったのでトライしてみた。

11.2.1: LAB: All permutations of names

Write a program that lists all ways people can line up for a photo (all permutations of a list of Strings). The program will read a list of one word names into ArrayList nameList (until -1), and use a recursive method to create and output all possible orderings of those names separated by a comma, one ordering per line.

import java.util.Scanner;

import java.util.ArrayList;

public class PhotoLineups {

   // Method to create and output all permutations of the list of names

   public static void printAllPermutations(ArrayList<String> permList, ArrayList<String> nameList) {

      // Base case: when nameList is empty, print the current permutation

      if (nameList.size() == 0) {

         System.out.println(String.join(", ", permList));

         return;

      }

      // Iterate through the list and recursively generate all permutations

      for (int i = 0; i < nameList.size(); i++) {

         // Select the current name

         String currentName = nameList.get(i);

         // Create a new list of remaining names by removing the current name

         ArrayList<String> remainingNames = new ArrayList<>(nameList);

         remainingNames.remove(i);

         // Add the current name to the permutation list

         permList.add(currentName);

         // Recurse with the remaining names and current permutation list

         printAllPermutations(permList, remainingNames);

         // Backtrack: remove the last added name to try the next permutation

         permList.remove(permList.size() - 1);

      }

   }

   public static void main(String[] args) {

      Scanner scnr = new Scanner(System.in);

      ArrayList<String> nameList = new ArrayList<>();

      ArrayList<String> permList = new ArrayList<>();

      String name;

      // Read names from the user until "-1" is entered

      while (true) {

         name = scnr.next().trim();

         if (name.equals("-1")) {

            break;  // Stop reading names when "-1" is encountered

         }

         nameList.add(name);  // Add name to the list

      }

      // Generate and print all permutations of the list of names

      printAllPermutations(permList, nameList);

   }

}

参照：

https://www.youtube.com/watch?v=IBXAgPP7GDU