Dixit Infotech Services Oracle Database Administrator Interview Questions and Answers

Round duration - 40 minutes
Round difficulty - Medium

Asked about time complexity of algorithm, puzzles, DBMS, cutting edge technologies etc. What are indexes?

Q1. 
Flip Bits Problem Explanation
Given an array of integers ARR of size N, consisting of 0s and 1s, you need to select a sub-array and flip its bits. Your task is to return the maximum count of 1s that can b...read more
Ans. 
Given an array of 0s and 1s, find the maximum count of 1s by flipping a sub-array at most once.
• Iterate through the array and keep track of the maximum count of 1s obtained by flipping a sub-array.

• Consider flipping a sub-array from index i to j and calculate the count of 1s in the resulting array.

• Return the maximum count of 1s obtained by flipping a sub-array at most once.
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Round duration - 20 minutes
Round difficulty - Medium

Asked 1 standard algorithm

Q1. 
Number of Islands Problem Statement
You are provided with a 2-dimensional matrix having N rows and M columns, containing only 1s (land) and 0s (water). Your goal is to determine the number of islands in t...read more
Ans. 
Count the number of islands in a 2D matrix of 1s and 0s.
• Iterate through the matrix and perform depth-first search (DFS) to find connected 1s.

• Mark visited cells to avoid redundant traversal.

• Increment island count whenever a new island is encountered.
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Round duration - 90 minutes
Round difficulty - Medium

A time range is given you can attempt with in that time and once started you cant resume .

Q1. 
Sort String with Alternate Lower and Upper Case
Given a string STR containing both lowercase and uppercase letters, the task is to sort the string so that the resulting string contains uppercase and lower...read more
Ans. 
Sort a string with alternate lowercase and uppercase letters in sorted order.
• Create two separate arrays for lowercase and uppercase letters.

• Sort both arrays individually.

• Merge the two arrays alternately to form the final sorted string.
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Q2. 
Remove Invalid Parentheses
Given a string containing only parentheses and letters, your goal is to remove the minimum number of invalid parentheses to make the input string valid and return all possible v...read more
Ans. 
Given a string with parentheses and letters, remove minimum invalid parentheses to make it valid and return all possible valid strings.
• Use BFS to explore all possible valid strings by removing parentheses one by one

• Keep track of visited strings to avoid duplicates

• Return all unique valid strings obtained after removing minimum number of parentheses
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Q3. 
Nth Fibonacci Number Problem Statement
Calculate the Nth term in the Fibonacci sequence, where the sequence is defined as follows: F(n) = F(n-1) + F(n-2), with initial conditions F(1) = F(2) = 1.
Input:
...read more
Ans. 
Calculate the Nth Fibonacci number efficiently using dynamic programming.
• Use dynamic programming to store previously calculated Fibonacci numbers to avoid redundant calculations.

• Start with base cases F(1) and F(2) as 1, then iterate to calculate F(N) efficiently.

• Time complexity can be optimized to O(N) using dynamic programming.

• Example: For N = 5, the 5th Fibonacci number is 5.
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Q4. 
Find the Kth Row of Pascal's Triangle Problem Statement
Given a non-negative integer 'K', determine the Kth row of Pascal’s Triangle.
Example:
Input:
K = 2
Output:
1 1
Input:
K = 4
Output:
1 4 6 ...read more
Ans. 
To find the Kth row of Pascal's Triangle given a non-negative integer K.
• Create an array to store the values of the Kth row of Pascal's Triangle

• Use the formula C(n, k) = C(n-1, k-1) + C(n-1, k) to calculate the values

• Return the array as the output
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There were 19 questions consists of aptitude and technical subject. Then 2 codes were there . Then 1 code of SQL query .

Q1. Technical Interview 45min Introduce yourself Projects included in Resume Discussion on Projects Mentioned in projects Two coding questions -----+all+permutation+of+a+string+geeksforgeeks -----/ 2 Puzzle
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Q2. -----+all+permutation+of+a+string+geeksforgeeks -----/
Ans. 
Generate all permutations of a given string using recursion and backtracking.
• Use recursion to generate all possible permutations of the string.

• Use backtracking to backtrack and explore all possible combinations.

• Store each permutation in an array of strings.
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Q1. Technical Interview 45 min Introduce yourself Projects included in Resume Discussion on Projects Mentioned in projects Two coding questions -----+a+string+geeksforgeeks -----/ 3 Puzzle
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Q1. Technical + HR 1 hrs Introduce yourself Projects included in Resume Discussion on Projects Mentioned in projects 3 coding questions ----- ----- ----- 2 Puzzle
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Simple DBMS and DSA Questions

Q1. String Manipulations
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Q2. Linked lists questions
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