<p>Given two strings <code>a</code> and <code>b</code>, return <em>the minimum number of times you should repeat string </em><code>a</code><em> so that string</em> <code>b</code> <em>is a substring of it</em>. If it is impossible for <code>b</code>​​​​​​ to be a substring of <code>a</code> after repeating it, return <code>-1</code>.</p>

<p><strong>Notice:</strong> string <code>&quot;abc&quot;</code> repeated 0 times is <code>&quot;&quot;</code>, repeated 1 time is <code>&quot;abc&quot;</code> and repeated 2 times is <code>&quot;abcabc&quot;</code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> a = &quot;abcd&quot;, b = &quot;cdabcdab&quot;
<strong>Output:</strong> 3
<strong>Explanation:</strong> We return 3 because by repeating a three times &quot;ab<strong>cdabcdab</strong>cd&quot;, b is a substring of it.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> a = &quot;a&quot;, b = &quot;aa&quot;
<strong>Output:</strong> 2
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= a.length, b.length &lt;= 10<sup>4</sup></code></li>
	<li><code>a</code> and <code>b</code> consist of lowercase English letters.</li>
</ul>

class Solution {
public:
    bool isSubstring(string &s,string &p){
        int n = s.length();
        int m = p.length();
        vector<int> lps(m);
        lps[0] = 0;
        for (int i = 1; i < m; i++)
        {
            int j = lps[i - 1];
            if (p[i] == p[j])
            {
                j++;
            }
            while (j > 0 and p[i] != p[j])
            {
                j = lps[j - 1];
            }
            lps[i] = j;
        }
         int i = 0, j = 0;
        while (i < n)
        {
            if (s[i] == p[j])
            {
                i++;
                j++;
            }
            if (j == m)
            {
                return true;
                // return 0;
            }
            else if (s[i] != p[j] and i < n)
            {
                if (j > 0)
                {
                    j = lps[j - 1];
                }
                else
                {
                    i++;
                }
            }
        }
        return false;
    }
    int repeatedStringMatch(string a, string b) {
        int n=a.length();
        int m=b.length();
        map<char,int>mp;
        for(int i=0;i<n;i++) mp[a[i]]++;
        for(int i=0;i<m;i++) {
            if(mp[b[i]]==0) return -1;
        }
        string ns=a;
        int cnt=m/n+(m%n!=0);
        int c=cnt;
        while(c>1){
            a=a+ns;
            c--;
        }
        if(a.find(b)!=std::string::npos){
            return cnt;
        }
        a=a+ns;
        if(a.find(b)!=std::string::npos){
            return cnt+1;
        }
        a=a+ns;
        if(a.find(b)!=std::string::npos){
            return cnt+2;
        }
        return -1;
    }
};
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