Leetcode挑战题——Repeated String Match

Repeated String Match

Given two strings A and B, find the minimum number of times A has to be repeated such that B is a substring of it. If no such solution, return -1.

For example, with A = "abcd" and B = "cdabcdab".

Return 3, because by repeating A three times (“abcdabcdabcd”), B is a substring of it; and B is not a substring of A repeated two times ("abcdabcd").

Note:
The length of A and B will be between 1 and 10000.

 2*$str2_len && strstr($str1,$str2) === false){
            return -1;
        }else{
            $str1 .= $a;
            return repeatedStringMatch($str1,$str2,++$num,$a);//递归调用函数，累加重复数，注意这里不能用$num++

        }
    }
    echo repeatedStringMatch($str1,$str2);
?>

结果：3

若有不对之处，希望各位批评指正，谢谢！