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class Solution {
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 public:
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  bool isMatch(string s, string p) {
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    return helper(s, p, 0, 0);
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  }
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  bool helper(string s, string p, int i, int j) {
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    if (j == p.length()) return i == s.length();
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    bool first_match = (i < s.length() && (s[i] == p[j] || p[j] == '.'));
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    if (j + 1 < p.length() && p[j + 1] == '*') {
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      return (helper(s, p, i, j + 2) || (first_match && helper(s, p, i + 1, j)));
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    } else {
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      return (first_match && helper(s, p, i + 1, j + 1));
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    }
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  }
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};