Lstmxx的空间

530. 二叉搜索树的最小绝对差

给你一棵所有节点为非负值的二叉搜索树，请你计算树中任意两节点的差的绝对值的最小值。

/**
 * Definition for a binary tree node.
 * class TreeNode {
 *     val: number
 *     left: TreeNode | null
 *     right: TreeNode | null
 *     constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
 *         this.val = (val===undefined ? 0 : val)
 *         this.left = (left===undefined ? null : left)
 *         this.right = (right===undefined ? null : right)
 *     }
 * }
 */


function getMinimumDifference(root: TreeNode | null): number {
  let min = Infinity
  let pre = -1
  function findDistanceMin(node: TreeNode) {
    if (node === null) return
    findDistanceMin(node.left)
    if (pre !== -1) {
      const dis = node.val - pre
      min = Math.min(dis, min)
    }
    pre = node.val
    findDistanceMin(node.right)
  }
  findDistanceMin(root)
  return min
};