# Author Archives

### Arpan Das

SDE II Amazon
Bengaluru, Karnataka, India

## Smallest Common Region

You are given some lists of regions where the first region of each list includes all other regions in that list. Naturally, if a region X contains another region Y then X is bigger than Y. Also by definition a region X contains itself.

## String to Integer (atoi)

Here we are going to write our own atoi() implementation in Java. Remember in Java you convert a string to an integer using the parseInt method of the Java Integer class. The parseInt method converts the String to an int, and throws a NumberFormatException if the string can’t be converted to an int type.

## How to sort HashMap in Java by Keys ?

How to sort HashMap in Java by Keys

## House Robber

You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from robbing each of them is that adjacent houses have security system connected and it will automatically contact the police if two adjacent houses were broken into on the same night.

## Path with Maximum Gold

In a gold mine grid of size m * n, each cell in this mine has an integer representing the amount of gold in that cell, 0 if it is empty.

## Longest Palindromic Substring

Given a string s, return the longest palindromic substring in s.

## Top K Frequent Elements

Given a non-empty array of integers, return the k most frequent elements.

## Valid Parentheses

Imagine you are writing a small compiler for your college project and one of the tasks (or say sub-tasks) for the compiler would be to detect if the parenthesis are in place or not.

## Broken Calculator

On a broken calculator that has a number showing on its display, we can perform two operations

## Range SUM of BST

Given the root node of a binary search tree, return the sum of values of all nodes with a value between L and R (inclusive). The binary search tree is guaranteed to have unique values.