Minimum Non-Zero Product of the Array Elements LeetCode solution in Java

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class Solution {
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  public int mod = 1_000_000_007;
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  public int minNonZeroProduct(int p) {
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    if (p == 1) return 1;
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    long mx = (long) (Math.pow(2, p)) - 1;
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    long sm = mx - 1;
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    long n = sm / 2;
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    long sum = rec(sm, n);
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    return (int) (sum * (mx % mod) % mod);
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  }
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  public long rec(long val, long n) {
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    if (n == 0) return 1;
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    if (n == 1) return (val % mod);
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    long newVal = ((val % mod) * (val % mod)) % mod;
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    if (n % 2 != 0) {
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      return ((rec(newVal, n / 2) % mod) * (val % mod)) % mod;
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    }
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    return rec(newVal, n / 2) % mod;
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  }
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}