Koo App Senior Android Developer Interview Questions and Answers

Kadance algorithm and find the middle of the linklist

More on java and Python based coding questions

Q1. Behavioural questions were asked
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Q2. What are your expectations from this job
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Q3. What are your plans ahead
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Q4. Where do you see yourself in 5 years ahead
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Leecode medium level question

Leetcode Hard level Question

Q1. This is cto round asked some interview questions
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Q1. Explain hoisting in js
Ans. 
Hoisting in JavaScript is the behavior where variable and function declarations are moved to the top of their containing scope during the compilation phase.
• Variable declarations are hoisted to the top of their scope, but not their assignments.

• Function declarations are fully hoisted, meaning they can be called before they are declared.

• Hoisting can lead to unexpected behavior if not understood properly.
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Q2. Explain closures in js
Ans. 
Closures in JavaScript allow functions to access variables from their outer scope even after the outer function has finished executing.
• Closures are created when a function is defined within another function and the inner function has access to the outer function's variables.

• Closures can be used to create private variables and functions in JavaScript.

• Closures can also be used to maintain state in asynchronous operations
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Q1. Javascript polyfills
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Computer Fundamentals

Q1. Flatten a binary tree
Ans. 
Flatten a binary tree by converting it into a linked list in-place.
• Use a recursive approach to flatten the binary tree.

• Traverse the tree in a pre-order manner and keep track of the previous node.

• Set the left child of each node to null and the right child to the next node in the linked list.

• Example: Input: 1 -> 2 -> 5 -> 3 -> 4 -> null, Output: 1 -> null -> 2 -> null -> 3 -> null -> 4 -> null -> 5 -> null
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Round duration - 60 Minutes
Round difficulty - Easy

Formal Introduction.
Asked About Projects.
Difference between SQL and NoSQL. Pros and Cons. Where should we use SQL and NoSQL.
Given a problem, I have to make a SQL Database structure and then interviewer told me to convert it into NoSQL.
asked coding questions

Q1. 
Search In Rotated Sorted Array Problem Statement
Given a sorted array of distinct integers that has been rotated clockwise by an unknown amount, you need to search for a specified integer in the array. Fo...read more
Ans. 
Implement a search function to find a specified integer in a rotated sorted array.
• Implement a binary search algorithm to find the target integer in the rotated sorted array.

• Handle the cases where the target integer may lie in the left or right half of the rotation.

• Keep track of the mid element and adjust the search range based on the rotation.

• Return the index of the target integer if found, else return -1.
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Q2. 
Zigzag Binary Tree Traversal Problem
Given a binary tree, compute the zigzag level order traversal of the node values in the tree. The zigzag traversal requires traversing levels from left to right, then ...read more
Ans. 
Zigzag level order traversal of a binary tree is computed by alternating between left to right and right to left traversal at each level.
• Use a queue to perform level order traversal of the binary tree.

• Maintain a flag to switch between left to right and right to left traversal at each level.

• Store the node values in a list while traversing and alternate the order based on the flag.

• Example: For input 1 2 3 4 -1 5 6 -1 7 -...read more
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Q1. JS basics, promise, async await, debounce, etc.
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Round duration - 60 Minutes
Round difficulty - Easy

This round consisted of DSA questions and they were looking for good coding practices.

Q1. 
Aggressive Cows Problem Statement
Given an array representing positions of stalls and an integer ‘K’ representing the number of aggressive cows, determine the largest minimum distance between any two cows ...read more
Ans. 
The problem is to assign aggressive cows to stalls in a way that maximizes the minimum distance between any two cows.
• Sort the array of stall positions in ascending order.

• Use binary search to find the largest minimum distance between cows.

• Check if it is possible to assign cows with this minimum distance by iterating through the sorted array.

• If it is possible, update the maximum distance and continue binary search for a ...read more
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Q2. 
Next Greater Element Problem Statement
Given a list of integers of size N, your task is to determine the Next Greater Element (NGE) for every element. The Next Greater Element for an element X is the firs...read more
Ans. 
The task is to find the next greater element for each element in the given array.
• Iterate through the array from right to left.

• Use a stack to keep track of the elements that are greater than the current element.

• For each element, pop elements from the stack until a greater element is found or the stack is empty.

• If a greater element is found, it is the next greater element for the current element.

• If the stack becomes empt...read more
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Round duration - 60 Minutes
Round difficulty - Easy

This round consisted of React related questions, javascript questions.

Q1. Tell about event loop.
Ans. 
Event loop is a mechanism in programming that allows for asynchronous execution of code by continuously checking for and handling events.
• Event loop is commonly used in JavaScript to handle asynchronous operations.

• It allows for non-blocking I/O operations by delegating tasks to the operating system.

• Event loop continuously checks the event queue for any pending events and executes them in a sequential manner.

• Example: In ...read more
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