Paytm Android Developer Interview Questions and Answers

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.

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.

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 given example, the optimal solution is to select stones wit...read more

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.

To set equal spacing between childs of constraint layout, use the chain style property.

• Create a chain of the views that need equal spacing using the chain style property.

• Set the chain style to spread inside the constraint layout.

• Adjust the margins of the views to control the spacing.

• Use the layout_constraintHorizontal_chainStyle or layout_constraintVertical_chainStyle attribute to set the chain style.

• Example: app:layout_constraintHorizontal_chainStyle="spread"

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 application and is available throughout the application.

• Activity...read more

The garbage collector in Android automatically manages memory by reclaiming unused objects.

• Garbage collector identifies objects that are no longer referenced by the program.

• It frees up memory occupied by these objects, making it available for future use.

• The process involves marking objects as reachable or unreachable, and then reclaiming memory from unreachable objects.

• Garbage collection can be triggered automatically or manually using System.gc().

• Example: If an object is cre...read more

Dagger is required for dependency injection in Android development.

• Dagger helps in managing dependencies and reduces boilerplate code.

• It provides compile-time safety and improves code readability.

• Dagger also helps in testing and modularizing the codebase.

• It is widely used in Android development for building scalable and maintainable apps.