Create 0096-unique-binary-search-trees.js

Author: aadil42

javascript/0096-unique-binary-search-trees.js

@@ -0,0 +1,26 @@
+/**
+ * Time O(n^2) | Space O(n) | n^2 because of the inner loop which runs from 0 to n on each call.
+ * DFS | DP | Recursion | Tree
+ * https://leetcode.com/problems/unique-binary-search-trees/
+ * @param {number} n
+ * @return {number}
+ */
+var numTrees = function(n) {
+    
+    const cache = {};
+
+    const dfs = (n) => {
+        if(n <= 1) return 1;
+        if(cache[n]) return cache[n];
+
+        let total = 0;
+        for(let i = 0; i < n; i++) {
+            total += dfs(i) * dfs(n-1-i);
+        }
+
+        cache[n] = total;
+        return total;
+    }
+
+    return dfs(n);
+};