Oracle Software Developer Interview Questions, Process, and Tips

Round duration - 60 minutes
Round difficulty - Medium

The coding test was conducted on Hackerrank platform. The test was in the evening. There were two coding questions of medium difficulty. The test was proctored, our webcam was on but not the mic. Also we were not allowed to switch tabs.
500+ students sat in this round out which 20 were shortlisted for the next interview round.

Q1. 
Graph Coloring Problem
You are given a graph with 'N' vertices numbered from '1' to 'N' and 'M' edges. Your task is to color this graph using two colors, such as blue and red, in a way that no two adjacen...read more
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Q2. 
Count Inversions Problem Statement
Given an integer array ARR of size N, your task is to find the total number of inversions that exist in the array.
An inversion is defined for a pair of integers in the...read more
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Round duration - 60 minutes
Round difficulty - Medium

In this round, 2 interviewers were present. They shared Docs in which we had to write code. Our camera was on.

Q1. 
Sum Tree Conversion
Convert a given binary tree into its sum tree. In a sum tree, every node's value is replaced with the sum of its immediate children's values. Leaf nodes are set to 0. Finally, return th...read more
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Q2. 
Convert a Number to Words
Given an integer number num, your task is to convert 'num' into its corresponding word representation.
Input:
The first line of input contains an integer ‘T’ denoting the number o...read more
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Round duration - 30 minutes
Round difficulty - Easy

This was HR round but consisted problems related to core subjects too.

Round duration - 30 minutes
Round difficulty - Easy

Q1. 
Search in a Row-wise and Column-wise Sorted Matrix Problem Statement
You are given an N * N matrix of integers where each row and each column is sorted in increasing order. Your task is to find the positi...read more
Ans. Brute Force
• Run a loop from i = 0 to N - 1, to check each row.
  • Run a loop from j = 0 to N - 1, to check each element of the row.
    • If there is a match, return {i, j}.
• If the element is not found in the entire matrix, return {-1, -1}
Space Complexity: O(1)Explanation:
O(1).
 
Since only constant extra space is required.
Time Complexity: O(n^2)Explanation:
O(N ^ 2), where ‘N’ is the number of rows or columns in the matrix.
&nb...read more
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Q2. 
Valid Parenthesis Problem Statement
Given a string str composed solely of the characters "{", "}", "(", ")", "[", and "]", determine whether the parentheses are balanced.
Input:
The first line contains ...read more
Ans. Valid Parenthesis
Make use of the stack. Traverse the string and push the current character in the stack if it is an opening brace else pop from the stack If it is the corresponding starting brace for current closing brace then move to the next character of the string otherwise return false.
 
If after complete traversal if the stack is empty then the string is balanced else it is not balanced.
 
Pseudo Code:
• Decla...read more
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Round duration - 30 minutes
Round difficulty - Easy

Q1. 
Subarray Challenge: Largest Equal 0s and 1s
Determine the length of the largest subarray within a given array of 0s and 1s, such that the subarray contains an equal number of 0s and 1s.
Input:
Input beg...read more
Ans. Brute Force
• We generate all the possible subarrays by using two nested loops.
• We can run two nested loops, the outer loop picks the starting element and the inner loop picks the ending element.
• The third loop considers all elements in between the starting and ending elements.
• Check if each subarray has equal number of 0s and 1s
• This can be easily done by considering 0 as -1 and 1 as 1 since the sum for equal numbers of 0s a...read more
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Q2. 
Inplace Rotate Matrix 90 Degrees Anti-Clockwise
You are provided with a square matrix of non-negative integers of size 'N x N'. The task is to rotate this matrix by 90 degrees in an anti-clockwise directi...read more
Ans. Cycle rotation
1. There are N/2  cycles in a matrix of size ‘N’.
2. We traverse in the matrix from the outermost cycle, i.e. (0,0) to innermost cycle i.e. ((N/2)-1, (N/2)-1).
3. For each cycle, we’ll swap the elements of the matrix in a group of four elements i.e. for each ‘i’ <= ‘j’ < ‘N-i-1’ for each 0 <= ‘i’ <= ‘(N/2)-1’ we swap:
   • ‘ARR[i] [j]’ with ‘ARR[j, N-1-i]’
   • ‘ARR[j, N-1-i]’ with ‘ARR[N-1-i, N-1-j]’
   • ‘ARR[N-1-i...read more
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Round duration - 120 Minutes
Round difficulty - Easy

The round was conducted in day around 3PM.

Q1. 
Partition Equal Subset Sum Problem
Given an array ARR consisting of 'N' positive integers, determine if it is possible to partition the array into two subsets such that the sum of the elements in both sub...read more
Ans. Brute Force
Approach: The key point to notice here is that we have to partition an array into two equal subsets sum so two equal subsets must have the sum equal to 'TOTALSUM'/2, where 'TOTALSUM' represents the sum of all elements in the given array, and also 'TOTALSUM' should be even as we cant partitioned an array into two equal if 'TOTALSUM' is odd,  So now the problem is to check if there is any subset in a give...read more
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Round duration - 30 Minutes
Round difficulty - Easy

The interview was preponed and was conducted at 9AM.
The interviewer was friendly and I had saw him earlier at pre-placement talk.

Q1. 
Convert Sentence to Pascal Case
Given a string STR, your task is to remove spaces from STR and convert it to Pascal case format. The function should return the modified STR.
In Pascal case, words are con...read more
Ans. Brute Force
We can iterate over the string “STR” and maintain the resultant string in “answer”. On each character check if that character is white space (‘ ’) then change the next character to uppercase and do not include white space in the string “answer”, else append that character in the string “answer”.
 
Algorithm:
 
• Create an empty string “answer”.
• Iterate over string “STR”, for each character
  • If the STR[i] ==...read more
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Q2. Write an SQL query to retrieve the Nth highest salary from a database.
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Round duration - 30 Minutes
Round difficulty - Easy

This round was conducted 15mins after 1st round.

Q1. 
Remove the Kth Node from the End of a Linked List
You are given a singly Linked List with 'N' nodes containing integer data and an integer 'K'. Your task is to delete the Kth node from the end of this Lin...read more
Ans. Using Lists
The naive solution is to process all the nodes from the front side of the linked list and keep adding a node to the list. Now we can easily remove the Kth node from the end of the list by simply replacing the next pointer of the ('LENGTH' - 'K' - 1)th node (0-based indexing from start) of the list with the ('LENGTH' - 'K' + 1)th node. This way we can remove the Kth node from the end of the linked list.
Space ...read more
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