用C++打印最长的公共子字符串的递归方法是什么

#include <iostream>
#include <string>

using namespace std;

string longestCommonSubstring(string str1, string str2) {
    if (str1.empty() || str2.empty()) {
        return "";
    }
    
    if (str1.back() == str2.back()) {
        return longestCommonSubstring(str1.substr(0, str1.length() - 1), str2.substr(0, str2.length() - 1)) + str1.back();
    } else {
        string result1 = longestCommonSubstring(str1.substr(0, str1.length() - 1), str2);
        string result2 = longestCommonSubstring(str1, str2.substr(0, str2.length() - 1));
        return (result1.length() > result2.length()) ? result1 : result2;
    }
}

int main() {
    string str1 = "abcdefg";
    string str2 = "defghij";
    
    string longestSubstring = longestCommonSubstring(str1, str2);
    
    cout << "Longest common substring: " << longestSubstring << endl;
    
    return 0;
}