1359. Count All Valid Pickup and Delivery Options

class Solution {
public:
    int countOrders(int n) {
        vector<int> dp(n + 1);
        dp[1] = 1;
        for(int i = 2; i <= n; ++i){
            int tn = (2 * i - 1);
            int sn = (tn * (tn + 1)) / 2;
            dp[i] = (long long)dp[i - 1] * sn % 1000000007;
        }
        return dp[n];
    }
};