lowest_common_ancestor_of_binary_tree.cpp

//24 ms 100%

/**
 * 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) return nullptr;
        if(root == p || root == q) return root;
        
        TreeNode* L = lowestCommonAncestor(root->left, p, q);
        TreeNode* R = lowestCommonAncestor(root->right, p, q);
        if(L && R) return root;
        return (L == nullptr) ? R : L;
    }

};