lowest-common-ancestor-of-a-binary-tree.cpp

//https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree/

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