求最长公共字串

 比如："abcdkkk" 和 "baabcdadabc"，两个字符串 求最长公共字串 也即“abcd” 输出返回字符串长度。

如图

public class Main {
    public static void main(String[] args) {
        int n = f("abcddkkk", "baabcddadabc");
        System.out.println(n);
    }

    public static int f(String s1, String s2) {
        char[] c1 = s1.toCharArray();
        char[] c2 = s2.toCharArray();
        int [][] arr = new int[c1.length+1][c2.length+1];
        int max = 0;
        for(int i=1;i<arr.length;i++){
            for(int j=1;j<arr[i].length;j++){
                if(c1[i-1] == c2[j-1]){
                    arr[i][j] = arr[i-1][j-1]+1;
                    if(arr[i][j]>max){
                        max = arr[i][j];
                    }
                }
            }
        }
        return max;
    }
}