LintCode 85. 在二叉查找树中插入节点

/**
 * Definition of TreeNode:
 * class TreeNode {
 * public:
 *     int val;
 *     TreeNode *left, *right;
 *     TreeNode(int val) {
 *         this->val = val;
 *         this->left = this->right = NULL;
 *     }
 * }
 */


class Solution {
public:
    /*
     * @param root: The root of the binary search tree.
     * @param node: insert this node into the binary search tree
     * @return: The root of the new binary search tree.
     */
    TreeNode * insertNode(TreeNode * root, TreeNode * node) {
        // write your code here
        if(root==NULL)
        {
            root=node;
            return node;
        }
        TreeNode* p=root;
        while(p!=NULL)
        {
            if(node->val<p->val)
            {
                if(p->left==NULL)
                {
                    p->left=node;
                    return root;
                }
                else
                {
                    p=p->left;
                }
            }
            else
            {
                if(p->right==NULL)
                {
                    p->right=node;
                    return root;
                }
                else
                {
                    p=p->right;
                }
            }
        }
        return NULL;
        
    }
};