用C#解决LeetCode二叉树的最近公共祖先

题目

思路

逐层向下递归，直至找到公共祖先

代码块

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     public int val;
 *     public TreeNode left;
 *     public TreeNode right;
 *     public TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public TreeNode LowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
        if (root == null)
        {
            return null;
        }
        if (root.val == p.val || root.val == q.val)
        {
            return root;
        }
        var left = LowestCommonAncestor(root.left, p, q);
        var right = LowestCommonAncestor(root.right, p, q);
        if (left == null)
        {
            return right;
        }
        if (right == null)
        {
            return left;
        }
        return root;
    }
}

运行结果