TCS Interview Experience

Problems in Round: 1

Problem: One Odd Occurring

Given an array ‘ARR’ of ‘N’ integers, where all the elements occur an even number of times and only one number occurs an odd number of times. Find and return the number which occurs an odd number of times. For example: 'N' = 5, 'ARR' = [1, 2, 3, 2, 3] Output: 1 Except for number 1, all numbers occur an even number of times. Input Format : The first line contains a single integer, 'N', representing the size of the array. The second line contains 'N' space-separated integers. Output format : The only line contains a single integer representing the number occurring odd number of times. Note : You don't need to print anything. It has already been taken care of. Just implement the given function.

Step 1: I first understood the problem carefully. It was given that all coins originally appeared an even number of times, but after losing one coin, one denomination becomes odd. Step 2: I realized that the task is to find the number that occurs an odd number of times in the array. Step 3: Initially, I thought of using nested loops to count the frequency of each element and check which one has odd occurrences. Step 4: Then I optimized the approach using XOR logic. I used the property that the XOR of the same numbers cancels out (A ^ A = 0), and the XOR of all elements will give the number with odd frequency. Step 5: Finally, I applied XOR to all elements of the array and printed the result, which gave the missing coin denomination efficiently in O(n) time.

Problem Metadata

Problem Type: CODE

Average Solve Time: 13 minutes

Success Rate: 95%

Maximum Score: 40

Practice Topics: Arrays

Test Cases: 20

Default Language: cpp

Problems in Round: 1

Problem: Second Salary

Write a SQL query to find the second-highest salary from an Employee table without using the LIMIT clause.

Step 1: I first understood that I needed to find the second-highest distinct salary without using LIMIT, so I could not directly sort and pick the second value. Step 2: Initially, I thought of using ORDER BY with LIMIT, but since it was restricted, I moved to using subqueries. Step 3: I used a subquery to find the maximum salary from the table and then excluded that value. Step 4: After excluding the highest salary, I applied the MAX function again to the remaining values to get the second-highest salary. Step 5: This approach worked efficiently and handled duplicate values as well.