710263. Recursively print all sentences that can be formed from list of word lists
Recursively Print All Sentences That Can Be Formed From List of Word Lists
Summary
Given a list of word lists, we need to print all possible sentences that can be formed by combining words from these lists. This problem requires us to generate all permutations of the given word lists and then combine them into valid English sentences.
Detailed Explanation
To solve this problem, we will use recursion to generate all possible combinations of words from the given list of word lists. We will start with an empty sentence and recursively add words from each list until all words have been used or a complete sentence has been formed.
Here is the step-by-step breakdown of the solution:
- Initialize an empty sentence
sentence. - Iterate over each word list in the given list of word lists.
- For each word list, recursively generate all possible combinations of words and add them to
sentence. If a complete sentence has been formed, print it and return. - Backtrack by removing the last added word from
sentenceand repeat step 3 until all words have been used or a complete sentence has been formed.
Here is an ASCII art diagram illustrating the recursive approach:
+---------------+
| Given Word Lists |
+---------------+
|
|
v
+---------------+ +---------------+
| Recursively | | Combine Words |
| Generate | | into Sentence |
+---------------+ +---------------+
|
|
v
+---------------+ +---------------+
| Add Word to | | Backtrack and |
| Sentence | | Repeat |
+---------------+ +---------------+
Time complexity: O(n!), where n is the total number of words in all word lists. This is because we are generating all possible combinations of words.
Space complexity: O(n), as we need to store the current sentence and the list of word lists.
Optimized Solutions
Java
import java.util.ArrayList;
import java.util.List;
public class SentenceGenerator {
public static void generateSentences(List<List<String>> wordLists) {
generateSentences("", wordLists);
}
private static void generateSentences(String sentence, List<List<String>> wordLists) {
if (wordLists.isEmpty()) {
System.out.println(sentence);
return;
}
List<String> firstWordList = wordLists.get(0);
for (String word : firstWordList) {
List<List<String>> remainingWordLists = new ArrayList<>(wordLists);
remainingWordLists.remove(0);
generateSentences(sentence + " " + word, remainingWordLists);
}
}
public static void main(String[] args) {
List<List<String>> wordLists = new ArrayList<>();
// Add your word lists here
// ...
generateSentences(wordLists);
}
}