题解 | #在二叉树中找到两个节点的最近公共祖先#

/*
 * public class TreeNode {
 *   int val = 0;
 *   TreeNode left = null;
 *   TreeNode right = null;
 * }
 */

public class Solution {
    /**
     * 
     * @param root TreeNode类 
     * @param o1 int整型 
     * @param o2 int整型 
     * @return int整型
     */
    public int lowestCommonAncestor (TreeNode root, int o1, int o2) {
        // write code here
        return helper(root, o1,o2).val;
    }
    private TreeNode helper(TreeNode root, int o1, int o2){
        if(root == null ||root.val == o1 ||root.val == o2){
            return root;
        }
        TreeNode left = helper(root.left, o1,o2);
        TreeNode right = helper(root.right, o1,o2);
        if(left == null){
            return right;
        }
        if(right == null){
            return left;
        }
        return root;
    }
}