# 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)


## Tree: Level Order Traversal

Given a pointer to the root of a binary tree, you need to print the level order traversal of this tree. In level-order traversal, nodes are visited level by level from left to right. Complete the function levelOrder and print the values in a single line separated by a space. For example: 1 \ 2 \ 5 / \ 3 6 \ 4 F

## Binary Search Tree : Insertion

You are given a pointer to the root of a binary search tree and values to be inserted into the tree. Insert the values into their appropriate position in the binary search tree and return the root of the updated binary tree. You just have to complete the function. Input Format You are given a function, Node * insert (Node * root ,int data) { } Constraints No. of nodes in the tree <

## Tree: Huffman Decoding

Huffman coding assigns variable length codewords to fixed length input characters based on their frequencies. More frequent characters are assigned shorter codewords and less frequent characters are assigned longer codewords. All edges along the path to a character contain a code digit. If they are on the left side of the tree, they will be a 0 (zero). If on the right, they'll be a 1 (one). Only t

## Binary Search Tree : Lowest Common Ancestor

You are given pointer to the root of the binary search tree and two values v1 and v2. You need to return the lowest common ancestor (LCA) of v1 and v2 in the binary search tree. In the diagram above, the lowest common ancestor of the nodes 4 and 6 is the node 3. Node 3 is the lowest node which has nodes and as descendants. Function Description Complete the function lca in the editor b

## Swap Nodes [Algo]

A binary tree is a tree which is characterized by one of the following properties: It can be empty (null). It contains a root node only. It contains a root node with a left subtree, a right subtree, or both. These subtrees are also binary trees. In-order traversal is performed as Traverse the left subtree. Visit root. Traverse the right subtree. For this in-order traversal, start from

## Kitty's Calculations on a Tree

Kitty has a tree, T , consisting of n nodes where each node is uniquely labeled from 1 to n . Her friend Alex gave her q sets, where each set contains k distinct nodes. Kitty needs to calculate the following expression on each set: where: { u ,v } denotes an unordered pair of nodes belonging to the set. dist(u , v) denotes the number of edges on the unique (shortest) path between nodes a