1110-delete-nodes-and-return-forest.js

/**
 * Definition for a binary tree node.
 * function TreeNode(val) {
 *     this.val = val;
 *     this.left = this.right = null;
 * }
 */
/**
 * @param {TreeNode} root
 * @param {number[]} to_delete
 * @return {TreeNode[]}
 */
const delNodes = function(root, to_delete) {
  let rst = []
  let dfs = function(node, isRoot) {
    if (!node) return
    let isDel = to_delete.indexOf(node.val) !== -1
    if (node.left) node.left = dfs(node.left, isDel)
    if (node.right) node.right = dfs(node.right, isDel)
    if (isRoot && !isDel) rst.push(node)
    return isDel ? null : node
  }
  if (!root) return []
  dfs(root, true)
  return rst
}