leetcode 面试题 04.08. 首个共同祖先

c++

class Solution {
public:
    TreeNode* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) {
        if (!root) 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;
        if (!r) return l;
        return r; 
    }   
};

js

var lowestCommonAncestor = function(root, p, q) {
    if (!root) return null;
    if (root === p || root === q) return root;
    var l = lowestCommonAncestor(root.left, p, q);
    var r = lowestCommonAncestor(root.right, p, q);
    if (l && r) return root;
    if (!r) return l;
    return r;
};