Submit 96_UniqueBinarySearchTrees

Binlogo-Archive · Jul 15, 2020 · 25550e5 · 25550e5
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diff --git a/...dePlayground.playground/Pages/96_UniqueBinarySearchTrees .xcplaygroundpage/Contents.swift b/...dePlayground.playground/Pages/96_UniqueBinarySearchTrees .xcplaygroundpage/Contents.swift
@@ -0,0 +1,20 @@
+//: [Previous](@previous)
+
+import Foundation
+//return int(math.factorial(2*n)/math.factorial(n+1)/math.factorial(n))
+//var str = "Hello, playground"
+
+class Solution {
+    func numTrees(_ n: Int) -> Int {
+        (0..<n).reduce(1) { (c, i) in
+            let a = c * 2 * (2 * i + 1)
+            return a / (i + 2)
+        }
+    }
+}
+
+// Tests
+let s = Solution()
+s.numTrees(3)
+
+//: [Next](@next)
diff --git a/LeetCodePlayground.playground/contents.xcplayground b/LeetCodePlayground.playground/contents.xcplayground
@@ -112,5 +112,6 @@
         <page name='174_DungeonGame '/>
         <page name='350_IntersectionofTwoArraysII '/>
         <page name='120_Triangle'/>
+        <page name='96_UniqueBinarySearchTrees '/>
     </pages>
 </playground>