强密码检验器

// Java Solution with Streams
 
// 思路：
// 1. 使用流计算各种条件，如字符类型缺失和重复字符长度。
// 2. 使用流简化条件判断和数据处理。
 
import java.util.stream.Stream;
 
public class StrongPasswordChecker {
 
    public int strongPasswordChecker(String password) {
        int n = password.length();
        long hasLower = password.chars().filter(Character::isLowerCase).count();
        long hasUpper = password.chars().filter(Character::isUpperCase).count();
        long hasDigit = password.chars().filter(Character::isDigit).count();
        int missingTypes = (hasLower > 0 ? 0 : 1) + (hasUpper > 0 ? 0 : 1) + (hasDigit > 0 ? 0 : 1);
 
        int[] replaceCount = {0};
        int[] one = {0}, two = {0};
        char[] chars = password.toCharArray();
 
        for (int i = 0; i < n;) {
            int j = i;
            while (i < n && chars[i] == chars[j]) i++;
            int len = i - j;
            if (len >= 3) {
                replaceCount[0] += len / 3;
                if (len % 3 == 0) one[0]++;
                else if (len % 3 == 1) two[0]++;
            }
        }
 
        if (n < 6) return Math.max(missingTypes, 6 - n);
        else if (n <= 20) return Math.max(missingTypes, replaceCount[0]);
        else {
            int delete = n - 20;
            replaceCount[0] -= Math.min(delete, one[0] * 1) / 1;
            replaceCount[0] -= Math.min(Math.max(delete - one[0], 0), two[0] * 2) / 2;
            replaceCount[0] -= Math.max(delete - one[0] - 2 * two[0], 0) / 3;
            return delete + Math.max(missingTypes, replaceCount[0]);
        }
    }
}