LeetCode 236 Lowest Common Ancestor of a Binary Tree 二叉树两个子节点的最低公共父节点

 /**
  * Definition for a binary tree node.
  * struct TreeNode {
  *     int val;
  *     TreeNode *left;
  *     TreeNode *right;
  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
  * };
  */
 class Solution {
 public:
     TreeNode* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) {
         if(root==nullptr||p==nullptr||q==nullptr)
             return nullptr;
         if(root==p)
             return root;
         if(root==q)
             return root;
         TreeNode* left=lowestCommonAncestor(root->left,p,q);
         TreeNode* right=lowestCommonAncestor(root->right,p,q);
         if(left&&right)
             return root;
         return left?left:right;
     }
 };