SDE - 1

Given a binary tree with N number of nodes, check if that input tree is Partial BST (Binary Search Tree) or not. If yes, return true, return false otherwise.

A binary search tree (BST) is said to be a Partial BST if it follows the following properties.

• The left subtree of a node contains only nodes with data less than and equal to the node’s data.
• The right subtree of a node contains only nodes with data greater than and equal to the node’s data.
• Both the left and right subtrees must also be partial binary search trees.

Example:

Input:

Answer:

Level 1: 

All the nodes in the left subtree of 4 (2, 1, 3) are smaller 
than 4, all the nodes in the right subtree of the 4 (5) are 
larger than 4.

Level 2 :

For node 2:
All the nodes in the left subtree of 2 (1) are smaller than 
2, all the nodes in the right subtree of the 2 (3) are larger than 2.
For node 5:
The left and right subtree for node 5 is empty.

Level 3:

For node 1:
The left and right subtree for node 1 are empty.
For node 3:
The left and right subtree for node 3 are empty.
Because all the nodes follow the property of a Partial binary 
search tree, the above tree is a Partial binary search tree.

You have been given a string ‘A’ consisting of lower case English letters. Your task is to find the length of the longest palindromic subsequence in ‘A’.

A subsequence is a sequence generated from a string after deleting some or no characters of the string without changing the order of the remaining string characters. (i.e. “ace” is a subsequence of “abcde” while “aec” is not).

A string is said to be palindrome if the reverse of the string is the same as the actual string. For example, “abba” is a palindrome, but “abbc” is not a palindrome.

Two trains, separated by a distance of 80km, are running towards each other on the same track at a speed of 40 kmph. A bird takes its flight from train X and flies towards train Y at a constant speed of 100 kmph. Once it reaches train Y, it turns and start flying back toward strain X. The bird keeps flying to and forth till both the trains collide. Determine the distance travelled by the bird.

You are given a two-dimensional array/list of integers consisting of 0s and 1s. In the list, 1 represents land and 0 represents water.

The task is to find the number of distinct islands where a group of connected 1s(horizontally or vertically) forms an island.

Note:

Two islands are considered to be the same if and only if one island is equal to another(not rotated or reflected) i.e if we can translate one island on another without rotating or reflecting then it would be considered as the same islands. 

For example:

1 1 0
0 0 1
0 0 1

In this example, we have two islands and they would be considered as distinct islands as we can not translate them on one another even if they have the same no of 1's.

For example :

1 1 0 0 0 
1 1 0 0 0
0 0 0 1 1
0 0 0 1 1

In this example, we have two islands and they are the same as we can translate one island onto another island, so our answer should be 1.

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