236.二叉树的最近公共祖先 (Medium)*

class Solution {
public:
    TreeNode* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) {
        if(root == nullptr) {
            return nullptr;
        }
        if(root == p || root == q) {
            return root;
        }
        TreeNode *left = lowestCommonAncestor(root->left, p, q);
        TreeNode *right = lowestCommonAncestor(root->right, p, q);
        if(left == nullptr) {
            return right;
        }
        if(right == nullptr) {
            return left;
        }
        return root;
    }
};