class CommonOrder { static StringBuffer s1;// save string1 static StringBuffer s2;// save string2 static StringBuffer s3;// save commom string CommonOrder(String str1,String str2) { s1=new StringBuffer(str1); s2=new StringBuffer(str2); s3=new StringBuffer(); } /* 你编写的subsequenceOrder()函数的代码将被嵌在这里 */ StringBuffer getCommonString(){ return s3; } } public class Main{ public static void main(String[] args) { String X = null,Y = null; Scanner sc=new Scanner(System.in); if(sc.hasNext()) X=sc.nextLine(); if(sc.hasNext()) Y=sc.nextLine(); CommonOrder co=new CommonOrder(X,Y); co.subsequenceOrder(); StringBuffer str=co.getCommonString(); System.out.println(str+" "+str.length()); } }

以下是subsequenceOrder()函数的代码，它将找到s1和s2的最长公共子序列，并将其存储在s3中：

class CommonOrder {
    static StringBuffer s1;// save string1
    static StringBuffer s2;// save string2
    static StringBuffer s3;// save commom string

    CommonOrder(String str1, String str2) {
        s1 = new StringBuffer(str1);
        s2 = new StringBuffer(str2);
        s3 = new StringBuffer();
    }

    void subsequenceOrder() {
        int m = s1.length();
        int n = s2.length();
        int[][] dp = new int[m + 1][n + 1];

        for (int i = 1; i <= m; i++) {
            for (int j = 1; j <= n; j++) {
                if (s1.charAt(i - 1) == s2.charAt(j - 1)) {
                    dp[i][j] = dp[i - 1][j - 1] + 1;
                } else {
                    dp[i][j] = Math.max(dp[i - 1][j], dp[i][j - 1]);
                }
            }
        }

        int index = dp[m][n];
        int i = m, j = n;
        while (i > 0 && j > 0) {
            if (s1.charAt(i - 1) == s2.charAt(j - 1)) {
                s3.append(s1.charAt(i - 1));
                i--;
                j--;
                index--;
            } else if (dp[i - 1][j] > dp[i][j - 1]) {
                i--;
            } else {
                j--;
            }
        }

        s3.reverse();
    }

    StringBuffer getCommonString() {
        return s3;
    }
}

该算法使用动态规划来找到s1和s2的最长公共子序列。在找到最长公共子序列之后，它将反转s3，以便输出正确的顺序。