CF1581A CQXYM Count Permutations

R60225896

Luogu/CF1581A/CF1581A.cpp

@@ -0,0 +1,22 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+const int mod = 1000000007;
+
+int t, inv[100005];
+long long n, ans;
+
+int main() {
+    cin >> t;
+    while (t--) {
+        ans = 1;
+        cin >> n;
+        n *= 2;
+        while (n) {
+            ans = ans * n-- % mod;
+        }
+        cout << ans * 500000004 % mod << endl;
+    }
+    return 0;
+}