DSA/C++/LeetCode/0235.cpp at main · spycedcoffee/DSA · GitHub

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/**
 * 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* lca(TreeNode* root, TreeNode* p, TreeNode* q){

        if(!root)
            return NULL;

        if(root -> val == p -> val || root -> val == q -> val)
            return root;

        TreeNode* l = lca(root -> left, p, q);
        TreeNode* r = lca(root -> right, p, q);

        if(l && r)
            return root;

        else if(l)
            return l;

        else
            return r;
    }

    TreeNode* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) {
        return lca(root, p, q);
    }
};