Swiggy Software Developer Interview Questions, Process, and Tips

HAckerrank based test

Round duration - 120 Minutes
Round difficulty - Medium

Machine Coding Round
2 Hours in Total
15 Mins for Question Explaination and Doubts
1.5 Hours for coding
15 mins to discuss the approach 

Timing - 3 to 5 pm (They are flexible)
Interviewer was very patient and helped me understand the question

Round duration - 60 Minutes
Round difficulty - Medium

2 Data Strucutre Questions
Timing 5-6 pm (They are flexible)
Google Meet
Online IDE

Q1. Unique Binary Search Trees
You are given an integer ‘N’, your task is to return the number of structurally unique BST's (binary search trees) which have exactly 'N' nodes of unique values from ...read more
Ans. 
There can be 3 different type of trees which need to be identified and we need to take a bottom up approach
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Q2. Subsequences of String
You are given a string 'STR' containing lowercase English letters from a to z inclusive. Your task is to find all non-empty possible subsequences of 'STR'.
A Subsequ...read more
Ans. Binary Representation approach
The idea is to use bit patterns from binary representation of 1 to 2^length - 1. For a string of length N, use the binary representation of all the numbers from 1 to (2^N - 1). Start from left (Most significant bit) to right (Least significant bit) and append characters from input string which corresponds to bit value 1 in binary representation to the current subsequence.

For example: “abc”...read more
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Round duration - 60 Minutes
Round difficulty - Easy

HIRING MANAGER ROUND

Discussion about the organisation now questions

Round duration - 90 Minutes
Round difficulty - Medium

1 easy and 2 medium-hard DSA problems to solve

Q1. Hurdle Game
Once Kevin is playing a hurdle game in which he has to jump some hurdles to clear a particular level. Each level ‘i’ has ‘i’ hurdles (for example, level 6 has 6 hurdles).
You are provided wit...read more
Ans. Brute Force
The basic idea is to iterate through all the levels and keep subtracting the hurdles that Kevin has jumped. The steps are as follows:
 
1. Create two variables “hurdle” and “level” to count the hurdles that Kevin has jumped and to count the level cleared, respectively.
2. Iterate till the ”hurdle” becomes greater than ‘N’.
   • “hurdle” = “hurdle” + “level” + 1
   • “level” = “level” + 1
3. Return “level” - 1
Space Complexity: O...read more
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Q2. N Queens
You are given an integer 'N'. For a given 'N' x 'N' chessboard, find a way to place 'N' queens such that no queen can attack any other queen on the chessboard.
A ...read more
Ans. Backtracking
1. Instead of checking all the places on the chessboard, we can use backtracking and place queen row-wise or column-wise.
2. Suppose we place queens row-wise, and we start with the very first row. Place the queen and move to the next row until either there is a solution or there are no viable cells left.
3. As we backtrack, check to place the queen in the different columns of the same row.
4. When we can place a queen at ...read more
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Q3. Count Ways To Travel Triangular Pyramid
Bob has been given a triangular pyramid with its vertices marked as ‘O’, ‘X’, ‘Y’ and ‘Z’ and provided with another integer ‘N’. In a single step, Bob can go to any ...read more
Ans. Brute Force
The idea is very simple, as standing at any point we will always have three choices to move. So we will make a recursive function and call it for all three choices and decrease ‘N’ by 1 each time. So when ‘N’ will reach 0 then we will check the current position, if it is ‘O’ then we can say we have found a way.
 
Complete Algorithm :
• We will make a helper recursive function named ‘SOLVE’ which will receive...read more
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Round duration - 60 Minutes
Round difficulty - Medium

2 DSA problems and computer subject questions

Q1. Binary strings with no consecutive 1s.
You have been given an integer K.
Your task is to generate all binary strings of length K such that there are no consecutive 1s in the string. This means that the b...read more
Ans. Recursive Approach
Since we need to generate all substring which does not have consecutive 1s we can simply start adding new characters to the string until the length of the string is ‘K’ taking care that if the last character of the current string is ‘1’ we cannot add another ‘1’ as it will result in consecutive ‘1s.’ Otherwise, if the last character is ‘0’ we have 2 options either to add ‘1’ or ‘0’. We explore both th...read more
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Q2. Shuffle Two Strings
You are given three strings “A”, “B” and “C”. Your task is to check whether “C” is formed by an interleaving of A and B. C is said to be interleaving “A” and “B”, if the length of “C” i...read more
Ans. Brute-force, Recursion
Approach:
 
To solve this problem, let us solve a smaller problem first. Let’s assume that the length of the string A and B is one and the length of the string C is two. Now to check whether C is formed by interleaving A and B or not, we consider the last character of string C, and if this character matches neither with the character of the string A nor with the character of string B, then we r...read more
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Round duration - 60 Minutes
Round difficulty - Easy

DSA round

Q1. Ninja And Geometry
Ninja has been given 2 points ‘A’ and ’B’ that corresponds to the line ‘AB’ and ‘P’, ’Q’ that corresponds to line ‘PQ’ on a 2D plane. Ninja wants to find the intersection point of the ‘A...read more
Ans. Mathematics
The idea behind this approach is to derive the equation of both of the lines ‘AB’ and ‘PQ’ and check if the Slope of these two lines is equal or not. Following are the two cases:
• If the slope of ‘AB’ and ‘PQ’ is the same that means they are parallel so we return -1.
• Else there must a point where ‘AB’ and ‘PQ’ are intersecting.
For a better understanding of this approach, Assume that we have two points which are...read more
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Q2. Detect Cycle in a Directed Graph
Given a directed graph, check whether the graph contains a cycle or not. Your function should return true if the given graph contains at least one cycle, else return false...read more
Ans. 
1. Create the graph using the given number of edges and vertices.
2. Create a recursive function that initializes the current index or vertex, visited, and recursion stack.
3. Mark the current node as visited and also mark the index in the recursion stack.
4. Find all the vertices which are not visited and are adjacent to the current node. Recursively call the function for those vertices, If the recursive function returns...read more
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Round duration - 30 Minutes
Round difficulty - Easy

It is a managerial round

Q1. Networking Question
How does URL work and What is a load balancer.
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Round duration - 60 Minutes
Round difficulty - Easy

4 Questions which were of Easy, Medium, and Hard level.

Q1. Lowest Common Ancestor of a Binary Tree III
The node structure of a binary tree is modified such that each node has the reference to its parent node.
You are given two nodes: ‘N1’ and ‘N2’, of the above ...read more
Ans. 
This question is about finding the lowest common ancestor of two nodes in a binary tree with parent references.
• Traverse from the given nodes to their respective root nodes and store the paths in two separate lists.

• Compare the two lists and find the last common node.

• Return the last common node as the lowest common ancestor.
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Q2. Maximum subarray
Ninjas has been given an array. He wants to find a subarray such that the sum of all elements in the subarray is maximum.
Subarray 'A' is greater than sub-array 'B' if su...read more
Ans. 
The problem is to find a subarray with the maximum sum in a given array.
• Iterate through the array and keep track of the maximum sum and the current sum.

• If the current sum becomes negative, reset it to 0.

• Update the maximum sum if the current sum is greater.

• Also keep track of the start and end indices of the subarray with the maximum sum.

• Return the subarray using the start and end indices.
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Round duration - 50 Minutes
Round difficulty - Easy

Q1. Next Greater Element
For a given array/list of integers of size N, print the Next Greater Element(NGE) for every element. The Next Greater Element for an element X is the first element on the right side of...read more
Ans. 
The task is to find the next greater element for each element in an array.
• Iterate through the array from right to left.

• Use a stack to keep track of the elements that have a greater element to their right.

• 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 empty, the...read more
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Q2. Trapping Rain Water
You have been given a long type array/list 'ARR' of size 'N'. It represents an elevation map wherein 'ARR[i]' denotes the elevation of the 'ith' bar. Pri...read more
Ans. 
The question asks to find the total amount of rainwater that can be trapped in the given elevation map.
• Iterate through the array and find the maximum height on the left and right side of each bar.

• Calculate the amount of water that can be trapped at each bar by taking the minimum of the maximum heights on both sides and subtracting the height of the bar.

• Sum up the amount of water trapped at each bar to get the total amo
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Round duration - 30 Minutes
Round difficulty - Easy

It is just a formality round, asked basic questions like relocation and joining date etc