二叉树的最近公共祖先

class Solution

{public: TreeNode* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q)

{

if (root == q || root == p || root == NULL) return root;

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

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

 

if (left != NULL && right != NULL) return root;

 

if (left == NULL && right != NULL) return right;

else if (left != NULL && right == NULL) return left;

else { // (left == NULL && right == NULL) return NULL;

}

}};