lintcode 453 将二叉树拆成链表

/**
 * 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: a TreeNode, the root of the binary tree
     * @return: 
     */
    void flatten(TreeNode * root) {
        // write your code here
        if(root==NULL)
            return;
        TreeNode *l=root->left;
        TreeNode *r=root->right;
        flatten(root->left);
        flatten(root->right);
        if(root->left==NULL)
            return ;
        else {
            TreeNode *t=root->left;
            while(t->right)
                t=t->right;
            root->left=NULL;
            root->right=l;
            t->right=r;
        }
        return;
    }
};