leetcode.236-lowest-common-ancestor-of-a-binary-tree
lowest-common-ancestor-of-a-binary-tree 共同祖先
https://blog.csdn.net/zangdaiyang1991/article/details/94563586
/** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ class Solution { public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) { if (root == null || p == root || q == root) { return root; } TreeNode left = lowestCommonAncestor(root.left, p, q); TreeNode right = lowestCommonAncestor(root.right, p, q); if (left!=null && right!=null) { return root; } return left == null ? right : left; } }