Appstation Interview Questions and Answers

Q1. Data structures and kotlin basics to advance
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Q1. DSA: Put zeroes to end in an array
Ans. 
Move all zeroes to the end of an array of strings.
• Iterate through the array and keep track of the count of zeroes encountered.

• Swap non-zero elements with the first zero encountered to move zeroes to the end.
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Q2. What is context? Type of context in android, what are the differences
Ans. 
Context in Android refers to the current state of the application. There are different types of context in Android with varying scopes and lifecycles.
• Context is an abstract class in Android that allows access to application-specific resources and classes.

• There are three main types of context in Android: Application Context, Activity Context, and Service Context.

• Application Context is tied to the lifecycle of the applic...read more
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Round duration - 45 Minutes
Round difficulty - Easy

Q1. 
BST Iterator Problem Statement
You are tasked with creating a class named BSTIterator that acts as an iterator for the inorder traversal of a binary search tree. Implement the following functions:
1. BST...read more
Ans. 
Create a BSTIterator class for inorder traversal of a binary search tree.
• Implement a constructor that takes the root of the binary search tree and initializes the iterator.

• Implement next() function to return the next smallest element in the inorder traversal.

• Implement hasNext() function to check if there is a next element in the inorder traversal.

• Traverse the binary search tree in inorder to get the desired output.
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Q2. 
Integer to Roman Conversion
Given an integer N, convert it to its corresponding Roman numeral representation. Roman numerals comprise seven symbols: I, V, X, L, C, D, and M.
Example:
Input:
N = 2
Outp...read more
Ans. 
Convert an integer to its corresponding Roman numeral representation.
• Create a mapping of integer values to Roman numeral symbols.

• Iterate through the mapping in descending order of values and build the Roman numeral representation.

• Subtract the largest possible value from the integer at each step and append the corresponding Roman numeral symbol.

• Repeat until the integer becomes 0.
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Round duration - 45 Minutes
Round difficulty - Medium

Q1. 
Cube Sum Pairs Problem Statement
Given a positive integer N, find the number of ways to express N as a sum of cubes of two integers, A and B, such that:
N = A^3 + B^3
Ensure you adhere to the following c...read more
Ans. 
The problem involves finding the number of ways to express a given positive integer as a sum of cubes of two integers.
• Iterate through all possible values of A and B within the given constraints.

• Check if A^3 + B^3 equals the given N, increment the count if true.

• Handle the case where A = B separately to avoid counting duplicates.
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Q2. 
Colorful Knapsack Problem
You are given a set of 'N' stones, each with a specific weight and color. The goal is to fill a knapsack with exactly 'M' stones, choosing one stone of each color, so that the to...read more
Ans. 
The Colorful Knapsack Problem involves selecting one stone of each color to fill a knapsack with a given weight capacity, minimizing unused capacity.
• Iterate through the stones and keep track of the minimum weight for each color.

• Use dynamic programming to find the optimal solution by considering all possible combinations.

• Handle cases where the knapsack cannot be filled under the given conditions by returning -1.

• In the g...read more
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Round duration - 15 Minutes
Round difficulty - Easy