Inorder Successor - Amazon Top Interview Questions
Problem Statement :
Given a binary search tree root containing unique values, and an integer t, return the value of the inorder successor of t. That is, return the smallest value greater than t in the tree.
Note: you can assume that the inorder successor exists.
Bonus: solve it in \mathcal{O}(h)O(h) time and \mathcal{O}(1)O(1) space where h is the height of the tree.
Constraints
n ≤ 100,000 where n is the number of nodes in root
Example 1
Input
root = [2, [0, null, [1, null, null]], [3, null, [4, null, null]]]
t = 2
Output
3
Example 2
Input
root = [2, [0, null, [1, null, null]], [3, null, [4, null, null]]]
t = 1
Output
2
Solution :
Solution in C++ :
/**
* class Tree {
* public:
* int val;
* Tree *left;
* Tree *right;
* };
*/
int solve(Tree* root, int t) {
int ans = INT_MAX;
while (root != NULL) {
if (root->val > t) {
ans = min(ans, root->val);
root = root->left;
} else {
root = root->right;
}
}
return ans;
}
Solution in Python :
# class Tree:
# def __init__(self, val, left=None, right=None):
# self.val = val
# self.left = left
# self.right = right
class Solution:
def solve(self, root, t):
self.max_ele = float("inf")
self.traverse(root, t)
return self.max_ele
def traverse(self, root, t):
if not root:
return
if root.val <= t:
self.traverse(root.right, t)
else:
self.max_ele = min(self.max_ele, root.val)
self.traverse(root.left, t)
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