剑指 Offer 68 - II. 二叉树的最近公共祖先

解法一 递归

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