标签：思路 output clear tree change tab question row blog
Given a Binary Search Tree (BST), convert it to a Greater Tree such that every key of the original BST is changed to the original key plus sum of all keys greater than the original key in BST.
Example:
Input: The root of a Binary Search Tree like this:
5
/ 2 13
Output: The root of a Greater Tree like this:
18
/ 20 13
思路：注意利用BST中序遍历有序的特点，逆序遍历，在加和的时候一定要注意，先遍历右子树，处理当前节点，再遍历左子树。
1 void addGreaterSum(TreeNode*t, int* sum,bool* isfirst) 2 { 3 if (t == NULL) 4 return; 5 addGreaterSum(t->right, sum, isfirst); 6 if (t->right == NULL&&*isfirst) 7 { 8 *isfirst = false; 9 *sum = t->val; 10 } 11 else 12 { 13 int temp = t->val; 14 t->val += *sum; 15 *sum += temp; 16 } 17 18 addGreaterSum(t->left, sum, isfirst); 19 } 20 TreeNode* convertBST(TreeNode* root) 21 { 22 int sum = 0; 23 bool isfirst = true; 24 addGreaterSum(root, &sum, &isfirst); 25 return root; 26 }
LeetCode:Convert BST to Greater Tree
标签：思路 output clear tree change tab question row blog
原文地址：http://www.cnblogs.com/maclearning/p/6598499.html
