0235-lowest-common-ancestor-of-a-binary-search-tree.ts

/**
 * 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 lowestCommonAncestor(
    root: TreeNode | null,
    p: TreeNode | null,
    q: TreeNode | null
): TreeNode | null {
    let cur = root;

    while (cur) {
        if (p.val > cur.val && q.val > cur.val) {
            cur = cur.right;
        } else if (p.val < cur.val && q.val < cur.val) {
            cur = cur.left;
        } else {
            return cur;
        }
    }
}