diff --git a/javascript/0144-binary-tree-preorder-traversal.js b/javascript/0144-binary-tree-preorder-traversal.js new file mode 100644 index 000000000..8ba1f7cf8 --- /dev/null +++ b/javascript/0144-binary-tree-preorder-traversal.js @@ -0,0 +1,27 @@ +/** + * 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) + * } + */ +/** + * Pre-order-traversal + * Time O(n) | Space O(n) + * https://leetcode.com/problems/binary-tree-preorder-traversal/ + * @param {TreeNode} root + * @return {number[]} + */ +var preorderTraversal = function(root) { + + const dfs = (node, pre) => { + if (!node) return pre; + pre.push(node.val); + dfs(node.left, pre); + dfs(node.right, pre); + return pre; + } + + return dfs(root, []); +};