blob: 713c5829e38bfc039a166a8aac98b5d8d42a1646 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
|
// 1038. Binary Search Tree to Greater Sum Tree
#include "leetcode.h"
/*
* given the 'root' of a binary search tree, convert it to a greater tree such
* that every key o the original bst is changed to the original key plus the sum
* of all keys greater than the original key in bst. as a reminder, a binary
* search tree is a tree that satisfies the following constraints. the left
* subtree of a node contains only nodes with keys less than the node's key. the
* right subtree of a node contains only nodes with keys greater than the node's
* key. both the left and right subtrees also be binary search trees.
*/
struct TreeNode {
int val;
struct TreeNode *left;
struct TreeNode *right;
};
struct TreeNode *dfs(struct TreeNode *root) {
int accum = 0;
if (!root)
return NULL;
else {
dfs(root->right);
accum += root->val;
root->val = accum;
dfs(root->left);
return root;
}
}
struct TreeNode *bstToGst(struct TreeNode *root) { return dfs(root); }
|