import(solutions): IMPORT crupest/solutions COMPLETE.

1 files changed, 14 insertions, 0 deletions

diff --git a/works/solutions/leetcode/cpp/96.cpp b/works/solutions/leetcode/cpp/96.cpp
new file mode 100644
index 0000000..3757baa
--- /dev/null
+++ b/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;

+    }

+};