LeetCode: [226] Invert Binary Tree
Solution
For this problem we just solve the base problem for a tree with children, and then we use recursion to bubble up the changes.
/**
* 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 invertTree = function (root) {
if (!root) return null
const right = root.right
const left = root.left
root.left = invertTree(right)
root.right = invertTree(left)
return root
}