Lowest Common Ancestor of a Binary Tree

[fkdl0048]

/**
 * 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 || root == p || root == q) {
            return root;
        }

        TreeNode* left = lowestCommonAncestor(root->left, p, q);
        TreeNode* right = lowestCommonAncestor(root->right, p, q);

        if (left != nullptr && right != nullptr) {
            return root;
        }

        return (left != nullptr) ? left : right;
    }
};

• 진짜 알고리즘 같은 문제라 도움이 된듯 DFS 개념 정리에 가장 이해가 잘됨