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## Count zeros in a row wise and column wise sorted matrix

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Algorithm,
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Matrix
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## Search in a row wise and column wise sorted matrix

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Interviews,
Java,
Matrix,
Miscellaneous
- on 12:02:00
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Find number in sorted matrix

Given an n x n matrix, where every row and column is sorted in increasing order. Given a number k, how to decide whether this k is in the matrix. OR Search number in a row wise and column wise sorted matrix.

Given an n x n matrix, where every row and column is sorted in increasing order. Given a number k, how to decide whether this k is in the matrix. OR Search number in a row wise and column wise sorted matrix.

**Lets understand the problem statement graphically and it will be more clear,**## Find middle element of a linked list

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Algorithm,
Datastructure,
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Linked List
- on 05:33:00
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Find middle element of a linked list in Java

Given a singly linked list find middle of the linked list.

Find Nth node from last in a linked list

Given a singly linked list find middle of the linked list.

Find Nth node from last in a linked list

**Lets understand the problem statement graphically and it will be more clear,**## Convert Sorted Linked List to balanced BST

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Algorithm,
Binary Search Tree,
Binary Tree,
Datastructure,
Interviews,
Linked List
- on 10:03:00
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Convert Sorted Linked list to balanced Binary Search Tree

Convert sorted list to binary search tree

Lets simplify the question statement, Given a singly Linked List where elements are sorted in ascending order convert it to a height balanced BST.

Convert sorted list to binary search tree

Lets simplify the question statement, Given a singly Linked List where elements are sorted in ascending order convert it to a height balanced BST.

*A Binary Search Tree is called balanced if the height of left subtree and height of right subtree of Root differ by at most 1.***Lets understand the problem statement graphically and it will be more clear,**## Sorted Array to Balanced Binary Search Tree (BST)

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Binary Search Tree,
Binary Tree,
Interviews
- on 03:47:00
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Convert Sorted Array to Balanced Binary Search Tree

Given a sorted array, create a Balanced Binary Search Tree using array elements. A Binary Search Tree is called Balanced if, the height of left subtree and height of right subtree of Root differ by at most 1.

Given a sorted array, create a Balanced Binary Search Tree using array elements. A Binary Search Tree is called Balanced if, the height of left subtree and height of right subtree of Root differ by at most 1.

**Lets understand the problem statement graphically and it will be more clear,**## Clone linked list with next and random pointer

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Algorithm,
Datastructure,
Linked List
- on 05:47:00
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Clone linked list with next and random pointer

You are given a Doubly Link List with one pointer of each node pointing to the next node just like in a singly link list.The second pointer however can point to any node in the list and not just the previous node.

You are given a Doubly Link List with one pointer of each node pointing to the next node just like in a singly link list.The second pointer however can point to any node in the list and not just the previous node.

**Lets understand the problem statement graphically and it will be more clear,**## Serialize and Deserialize a Binary Tree

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Binary Tree,
Interviews
- on 10:55:00
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Serialize and Deserialize a Binary Tree

Design an algorithm to serialize and deserialize given Binary Tree. Serialization is to store tree in a File/String, so that it can be later restored.

Deserialization is reading tree back from file.

We need to Serialize given Binary Tree into String(So that we can write it to File or transfer it).

Also, we need to read the Serialized String and Deserialize it back to original Binary Tree.

Design an algorithm to serialize and deserialize given Binary Tree. Serialization is to store tree in a File/String, so that it can be later restored.

Deserialization is reading tree back from file.

**Lets understand the problem statement graphically and it will be more clear,**We need to Serialize given Binary Tree into String(So that we can write it to File or transfer it).

Also, we need to read the Serialized String and Deserialize it back to original Binary Tree.

## Trapping Rain Water between Towers

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Algorithm,
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- on 13:07:00
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How Much Water Can A Bar Graph Hold

Given an bar graph, encoded as an array of non-negative integers, calculate the units of water that this bar graph can hold.

Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it is able to trap after raining.

Input = [2, 0, 2]

Output = 2

Input = [3, 0, 0, 2, 0, 4]

Output = 10

Input = [0, 1, 0, 2, 1, 0, 1, 3, 2, 1, 2, 1]

Output = 6

Given an bar graph, encoded as an array of non-negative integers, calculate the units of water that this bar graph can hold.

**Let us put in technical terms,**Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it is able to trap after raining.

**Lets understand the problem statement graphically and it will be more clear,****Case 1:**Input = [2, 0, 2]

Output = 2

**Case 2:**Input = [3, 0, 0, 2, 0, 4]

Output = 10

**Case 3:**Input = [0, 1, 0, 2, 1, 0, 1, 3, 2, 1, 2, 1]

Output = 6