题解 | #二叉搜索树的最近公共祖先#

import java.util.*;

/*
 * public class TreeNode {
 *   int val = 0;
 *   TreeNode left = null;
 *   TreeNode right = null;
 *   public TreeNode(int val) {
 *     this.val = val;
 *   }
 * }
 */

public class Solution {
       int lastFather = -1; // 最近祖先
    public int lowestCommonAncestor (TreeNode root, int p, int q) {
        TreeNode currentNode = root;
        while(true){
            lastFather = currentNode.val;
		    // 当p、q有一人到达目的地，旅途结束
            if(p == lastFather || q == lastFather){
                break;
            }
            if(currentNode.val > p){
                if(currentNode.val > q){
				   // p、q的共同目的地：左子树
                    currentNode = currentNode.left;
                }else {
                    // 分别，旅途结束
                    break;
                }
            }else {
                if(currentNode.val < q){
				  // p、q的共同目的地：右子树
                    currentNode = currentNode.right;
                }else {
                    // 分别，旅途结束
                    break;
                }
            }
        }
        return lastFather;
    }
  

}