LINTCODE——Convert BST to Greater Tree

LINTCODE——Convert BST to Greater Tree

思路：考的就是另外一种遍历方式，记前序、中序、后序遍历分别为：MLR、LMR、LRM，那么题目就是要求你用RML这种遍历方式遍历更新就好了；

class Solution {private:    int s = 0;public:    /*     * @param root: the root of binary tree     * @return: the new root     */    TreeNode * convertBST(TreeNode * root) {        // write your code here        if(root == NULL)            return NULL;       convertBST(root -> right);       root -> val += s;       s = root -> val;       convertBST(root -> left);        return root;     }};