Closest Leaf in a Binary Tree

Description

null

Solution(javascript)

/**
 * Definition for a binary tree node.
 * function TreeNode(val) {
 *     this.val = val;
 *     this.left = this.right = null;
 * }
 */
/**
 * @param {TreeNode} root
 * @param {number} k
 * @return {number}
 */
const findClosestLeaf = function (root, k) {
  const adj = {}
  const set = (nodeA, nodeB) => {
    const a = nodeA.val
    const b = nodeB.val
    adj[a] = adj[a] || []
    adj[a].push(nodeB)
    adj[b] = adj[b] || []
    adj[b].push(nodeA)
  }
  let source = null
  const aux = (node) => {
    if (node.left) {
      set(node, node.left)
      aux(node.left)
    }
    if (node.val === k) {
      source = node
    }
    if (node.right) {
      set(node, node.right)
      aux(node.right)
    }
  }
  aux(root)
  let current = [source]
  const visited = {
    [k]: true,
  }
  while (current.length) {
    const next = []
    for (const node of current) {
      if (!node.left && !node.right) {
        return node.val
      }
      adj[node.val].forEach((nextNode) => {
        if (!visited[nextNode.val]) {
          visited[nextNode.val] = true
          next.push(nextNode)
        }
      })
    }
    current = next
  }
  return -1
}