字符串的前缀分数和

/*
 * 题目思路：
 * 1. 使用 Java Stream 来计算前缀的出现次数。
 * 2. 计算每个单词的前缀分数总和。
 */
import java.util.*;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

public class SolutionStream {
    public int[] prefixScores(String[] words) {
        Map<String, Long> prefixCount = Arrays.stream(words)
                .flatMap(word -> IntStream.rangeClosed(1, word.length()).mapToObj(i -> word.substring(0, i)))
                .collect(Collectors.groupingBy(prefix -> prefix, Collectors.counting()));

        return Arrays.stream(words)
                .mapToInt(word -> IntStream.rangeClosed(1, word.length())
                        .map(i -> prefixCount.get(word.substring(0, i)).intValue())
                        .sum())
                .toArray();
    }

    public static void main(String[] args) {
        SolutionStream sol = new SolutionStream();
        String[] words = {"abc", "ab", "bc", "b"};
        int[] result = sol.prefixScores(words);
        Arrays.stream(result).forEach(System.out::println);
    }
}