数青蛙

/*
 * The approach using Java Streams would involve the same logic as the regular Java implementation.
 * However, Java Streams are not typically used for this kind of stateful, sequential processing, especially for counting and updating states.
 * Thus, using Java Streams may not be appropriate or efficient for this problem.
 * Below is a conceptual demonstration that mirrors the logic in the standard Java solution without actual stream usage.
 */
import java.util.stream.IntStream;

public class FrogCroakStream {
    public int minNumberOfFrogs(String croakOfFrogs) {
        int[] croakCount = new int[5];
        int frogs = 0, maxFrogs = 0;
        for (char ch : croakOfFrogs.toCharArray()) {
            switch (ch) {
                case 'c':
                    croakCount[0]++;
                    frogs++;
                    maxFrogs = Math.max(maxFrogs, frogs);
                    break;
                case 'r':
                    if (croakCount[0] == 0) return -1;
                    croakCount[0]--;
                    croakCount[1]++;
                    break;
                case 'o':
                    if (croakCount[1] == 0) return -1;
                    croakCount[1]--;
                    croakCount[2]++;
                    break;
                case 'a':
                    if (croakCount[2] == 0) return -1;
                    croakCount[2]--;
                    croakCount[3]++;
                    break;
                case 'k':
                    if (croakCount[3] == 0) return -1;
                    croakCount[3]--;
                    croakCount[4]++;
                    frogs--;
                    break;
                default:
                    return -1;
            }
        }
        if (IntStream.of(croakCount).sum() != croakCount[4]) return -1;
        return maxFrogs;
    }
}