From dc1f0c4c0096013799416664894c5194dc7e1f52 Mon Sep 17 00:00:00 2001
From: Yuqian Yang <crupest@crupest.life>
Date: Fri, 28 Feb 2025 23:13:39 +0800
Subject: chore(store): move everything to store.

---
 store/works/solutions/leetcode/cpp/96.cpp | 14 ++++++++++++++
 1 file changed, 14 insertions(+)
 create mode 100644 store/works/solutions/leetcode/cpp/96.cpp

(limited to 'store/works/solutions/leetcode/cpp/96.cpp')

diff --git a/store/works/solutions/leetcode/cpp/96.cpp b/store/works/solutions/leetcode/cpp/96.cpp
new file mode 100644
index 0000000..3757baa
--- /dev/null
+++ b/store/works/solutions/leetcode/cpp/96.cpp
@@ -0,0 +1,14 @@
+class Solution {
+public:
+    // catalan number:
+    // f(n) = f(0) * f(n-1) + f(1) * f(n-2) + ... + f(n-1)*f(0)
+    // f(n) = 2(2n-1) * f(n-1) / (n+1)
+    // f(n) = C(2n, n) / (n+1)
+    int numTrees(int n) {
+        long long result = 1;
+        for (int i = 2; i <= n; i++) {
+            result = 2 * (2 * i - 1) * result / (i + 1);
+        }
+        return result;
+    }
+};
-- 
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