Tag Archives: Interview Questions

Internal working of HashMap in Java 8 & Beyond

By | |
Leave a comment

How HashMap internally works in java is the most asked interview question. Even with just 1–2 years of experience, you’ve likely used HashMap in your code. However, many developers are unaware of how it actually works under the hood.

This article dives deep into the internal mechanics of HashMap, explaining how the get, put, operations work behind the scenes. I am going to discuss the internal working of HashMap in java with diagrams and code examples.

How HashMap works internally video tutorial

What Really Happens When You Instantiate a HashMap in Java

→

Path Sum (Binary Tree Root to Leaf Path Sum)

By | | ,
Leave a comment

Binary Tree Root to Leaf Path Sum Equal to a Given Number.

Given a binary tree and a sum, Determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.

If path is found then return true else return false.

Note: What is leaf node? Any node whose left and right children is null is known as leaf node.

For example –

In this Binary tree, there exist a path from root-to-leaf node whose sum is equal to the given sum (which is 16).






Now, suppose if the given value of sum is 12. Then in this case we simply return false. As the root-to-leaf node path does not exist in a Binary tree whose sum is equal to 12.

→

Minimum Size Subarray Sum

By | | , , , ,
Leave a comment

Minimum Size Subarray Sum (Smallest subarray whose sum is greater than or equal to target).

Given an array of positive integers and a positive number k. Find the smallest contiguous subarray whose sum is either greater than or equal to k. If no subarray is found then return 0.

For example –

Example 1 –

  Input :  {7, 2, 1, 1, 6, 5},  k = 11

Output:  2 ( subarray {6, 5} has the minimum length )

Example 2 –

  Input : {1, 4, 3},   k = 12

Output: 0 (No subarray is possible)

→