Add solution #814

Author: JoshCrozier

Diff for: README.md

@@ -622,6 +622,7 @@
 811|[Subdomain Visit Count](./0811-subdomain-visit-count.js)|Medium|
 812|[Largest Triangle Area](./0812-largest-triangle-area.js)|Easy|
 813|[Largest Sum of Averages](./0813-largest-sum-of-averages.js)|Medium|
+814|[Binary Tree Pruning](./0814-binary-tree-pruning.js)|Medium|
 819|[Most Common Word](./0819-most-common-word.js)|Easy|
 821|[Shortest Distance to a Character](./0821-shortest-distance-to-a-character.js)|Easy|
 824|[Goat Latin](./0824-goat-latin.js)|Easy|

Diff for: solutions/0814-binary-tree-pruning.js

@@ -0,0 +1,32 @@
+/**
+ * 814. Binary Tree Pruning
+ * https://leetcode.com/problems/binary-tree-pruning/
+ * Difficulty: Medium
+ *
+ * Given the root of a binary tree, return the same tree where every subtree (of the given tree)
+ * not containing a 1 has been removed.
+ *
+ * A subtree of a node node is node plus every node that is a descendant of node.
+ */
+
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {TreeNode}
+ */
+var pruneTree = function(root) {
+  if (!root) return null;
+  root.left = pruneTree(root.left);
+  root.right = pruneTree(root.right);
+  if (!root.left && !root.right && root.val === 0) {
+    return null;
+  }
+  return root;
+};