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.
<?php
$str1 = "abcd";
$str2 = "cdabcdab";
function repeatedStringMatch($str1,$str2,$num = 1,$a = ''){
$str1_len = strlen($str1);
$str2_len = strlen($str2);
//判断字符串是否符号要求
if(!in_array($str1_len, range(1, 10000)) || !in_array($str2_len, range(1, 10000))){
return 'Invalid String!';
}
if($num == 1) $a = $str1;
if(strstr($str1,$str2)){
return $num;
}elseif($str1_len > 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!
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