Synopsys RTL Design Engineer Interview Questions and Answers

To check if a directed graph is cyclic or not

• Use Depth First Search (DFS) algorithm to traverse the graph

• Maintain a visited set to keep track of visited nodes

• Maintain a recursion stack to keep track of nodes in the current DFS traversal

• If a node is visited and is already in the recursion stack, then the graph is cyclic

• If DFS traversal completes without finding a cycle, then the graph is acyclic

Return a random byte from a stream of bytes with equal probability.

• Create a variable to store the count of bytes read

• Create a variable to store the current random byte

• For each byte read, generate a random number between 0 and the count of bytes read

• If the random number is 0, store the current byte as the random byte

• Return the random byte

Check if a binary tree is a binary search tree or not.

• Traverse the tree in-order and check if the values are in ascending order.

• For each node, check if its value is greater than the maximum value of its left subtree and less than the minimum value of its right subtree.

• Use recursion to check if all nodes in the tree satisfy the above condition.

Algorithm to find Nth-to-Last element in a singly linked list of unknown length

• Traverse the list and maintain two pointers, one at the beginning and one at Nth node from beginning

• Move both pointers simultaneously until the second pointer reaches the end of the list

• The first pointer will be pointing to the Nth-to-Last element

• If N=0, return the last element

• Parse the list only once

Print all possible permutations of an array of integers

• Use recursion to swap elements and generate permutations

• Start with the first element and swap it with each subsequent element

• Repeat the process for the remaining elements

• Stop when all elements have been swapped with the first element

• Print each permutation as it is generated

Design a stack that prints the minimum element pushed in O(1)

• Use two stacks, one for storing elements and another for storing minimums

• When pushing an element, compare it with the top of minimum stack and push the smaller one

• When popping an element, pop from both stacks

• To get the minimum element, just return the top of minimum stack

To find the starting point of a loop in a linked list, use Floyd's cycle-finding algorithm.

• Use two pointers, one moving at twice the speed of the other.

• When they meet, move one pointer to the head of the list and keep the other at the meeting point.

• Move both pointers one step at a time until they meet again, which is the starting point of the loop.

To find a number in a matrix where all rows and columns are sorted non-decreasingly. Complexity of the solution.

• Use binary search to find the number in each row and column

• Start from the top-right corner or bottom-left corner to optimize search

• Time complexity: O(m log n) or O(n log m) depending on the starting corner

The question is about finding the minimum steps to reach from a source string to a destination string using three operations.

• BFS and DFS are graph traversal techniques that can be used to solve this problem.

• BFS is typically used when finding the shortest path or exploring all possible paths in a graph.

• DFS is useful when searching for a specific path or exploring deeply into a graph.

• In this case, BFS can be used to find...read more

UDP is preferred over TCP in this project due to its low latency and lightweight nature.

• UDP is a connectionless protocol, which means it does not establish a direct connection between the sender and receiver.

• UDP is faster than TCP as it does not have the overhead of establishing and maintaining a connection.

• UDP is suitable for applications where real-time data transmission is crucial, such as video streaming or online ...read more

To clear the 7th bit in a 32-bit register, perform a bitwise AND operation with a mask that has all bits set to 1 except the 7th bit.

• Create a mask with the 7th bit set to 0 and all other bits set to 1

• Perform a bitwise AND operation between the register and the mask

• Store the result back in the register

Locate sum of 2 numbers in a linear array (unsorted and sorted) and their complexities

• For unsorted array, use nested loops to compare each element with every other element until the sum is found

• For sorted array, use two pointers approach starting from the beginning and end of the array and move them towards each other until the sum is found

• Complexity for unsorted array is O(n^2) and for sorted array is O(n)

Pointers are used to manipulate memory addresses and values in C++. Increment/decrement, address of and value at operators are commonly used.

• Incrementing a pointer moves it to the next memory location of the same data type

• Decrementing a pointer moves it to the previous memory location of the same data type

• The address of operator (&) returns the memory address of a variable

• The value at operator (*) returns the value sto

To determine if a point is inside or outside a rectangle, we check if the point's coordinates fall within the rectangle's boundaries.

• Check if the point's x-coordinate is greater than the left edge of the rectangle

• Check if the point's x-coordinate is less than the right edge of the rectangle

• Check if the point's y-coordinate is greater than the top edge of the rectangle

• Check if the point's y-coordinate is less than the b...read more

To find line that divides rectangle into 2 equal halves through a point inside it.

• Find the center of the rectangle

• Draw a line from the center to the given point

• Extend the line to the opposite side of the rectangle

• The extended line will divide the rectangle into 2 equal halves

There are multiple combinations of 8-bit and 16-bit signed numbers. How many such combinations are possible?

• There are 2^8 (256) possible combinations of 8-bit signed numbers.

• There are 2^16 (65,536) possible combinations of 16-bit signed numbers.

• To find the total number of combinations, we can add the number of combinations of 8-bit and 16-bit signed numbers.

• Therefore, the total number of possible combinations is 256 +

Find duplicates in an array of elements in 0(n) time and 0(1) space.

• Use the property of inputs to your advantage

• Iterate through the array and mark elements as negative

• If an element is already negative, it is a duplicate

• Return all the negative elements as duplicates