Count All Valid Pickup and Delivery Options LeetCode solution in Java

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class Solution {
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  public int countOrders(int n) {
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    long res = 1;
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    long mod = 1000000007;
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    for (int i = 1; i <= n; i++) {
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      res = res * (2 * i - 1) * i % mod;
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    }
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    return (int) res;
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  }
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}