# Map

## Largest Unique Number

Given an array of integers A, return the largest integer that only occurs once. If no integer occurs once, return -1.

## Strobogrammatic Number

A strobogrammatic number is a number that looks the same when rotated 180 degrees (looked at upside down). Write a function to determine if a number is strobogrammatic. The number is represented as a string.

## Single-Row Keyboard

Given a string keyboard of length 26 indicating the layout of the keyboard (indexed from 0 to 25), initially your finger is at index 0

## My Calendar I

Implement a MyCalendar class to store your events. A new event can be added if adding the event will not cause a double booking.

## Verifying an Alien Dictionary

In an alien language, surprisingly they also use english lowercase letters, but possibly in a different order. The order of the alphabet is some permutation of lowercase letters.

## Max Points on a Line

Given n points on a 2D plane, find the maximum number of points that lie on the same straight line.

## How to sort HashMap in Java by Keys ?

How to sort HashMap in Java by Keys

## Roman to Integer

Roman numerals are usually written from largest to smallest, and from left to right. However, the numeral for four is not IIII; instead, it is written as IV.

## Minimum Area Rectangle

Given a set of points in the xy-plane, determine the minimum area of a rectangle formed from these points, with sides parallel to the x and y axes. If there isn’t any rectangle, return 0.

## Design HashMap

Design a HashMap without using any built-in hash table libraries. To be specific, your design should include these functions: