Minimum Absolute Difference in BST
Problem Statement - link #
Given the root of a Binary Search Tree (BST), return the minimum absolute difference between the values of any two different nodes in the tree.
Examples #
Example 1:
Input: root = [4,2,6,1,3]
Output: 1
Example 2:
Input: root = [1,0,48,null,null,12,49]
Output: 1
Constraints #
- The number of nodes in the tree is in the range
[2, 10^4] 0 <= Node.val <= 10^5
Solutions #
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode() : val(0), left(nullptr), right(nullptr) {}
* TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
* TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
* };
*/
class Solution {
public:
int getMinimumDifference(TreeNode* root) {
int res = INT_MAX;
stack<TreeNode*> st;
TreeNode* cur = root, *pre = nullptr;
while(cur || st.size()) {
if(cur) {
st.push(cur);
cur = cur->left;
}
else {
cur = st.top();
st.pop();
if(pre) {
res = min(res, cur->val - pre->val);
}
pre = cur;
cur = cur->right;
}
}
return res;
}
};