Lstmxx的空间

938. 二叉搜索树的范围和

给定二叉搜索树的根结点 root，返回值位于范围 [low, high] 之间的所有结点的值的和。

链接

/**
 * 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 rangeSumBST(root: TreeNode | null, low: number, high: number): number {
  let total = 0
  function dfs(node: TreeNode | null) {
    if (node === null) return
    dfs(node.left)
    if (node.val >= low && node.val <= high) {
      total += node.val
    } else if (node.val > high) {
      return
    }
    dfs(node.right)
  }
  dfs(root)
  return total
};