Cutting Binary Search Tree - Amazon Top Interview Questions
Problem Statement :
Given a binary search tree root, an integer lo, and another an integer hi, remove all nodes that are not between [lo, hi] inclusive. Constraints n ≤ 100,000 where n is the number of nodes in root Example 1 Input root = [2, [1, [0, null, null], null], [4, [3, null, null], null]] lo = 3 hi = 4 Output [4, [3, null, null], null] Example 2 Input root = [5, [1, null, null], [9, [7, [6, null, null], [8, null, null]], [10, null, null]]] lo = 7 hi = 10 Output [9, [7, null, [8, null, null]], [10, null, null]]
Solution :
Solution in C++ :
Tree* solve(Tree* root, int lo, int hi) {
if (!root) return nullptr;
if (root->val < lo) return solve(root->right, lo, hi);
if (root->val > hi) return solve(root->left, lo, hi);
root->left = solve(root->left, lo, hi);
root->right = solve(root->right, lo, hi);
return root;
}
Solution in Python :
class Solution:
def solve(self, root, lo, hi):
if root is None:
return None
if root.val >= lo and root.val <= hi:
root.left = self.solve(root.left, lo, hi)
root.right = self.solve(root.right, lo, hi)
return root
elif root.val < lo:
return self.solve(root.right, lo, hi)
else:
return self.solve(root.left, lo, hi)
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