10+ Lucky Communications Interview Questions and Answers

The task is to print a string without any repeating characters.

• Iterate through the string and keep track of the characters seen so far.

• If a character is already seen, skip it.

• Otherwise, add it to the output string.

• Return the output string.

The angle between hour and minute hand of a clock at a given time.

• Calculate the angle made by the hour hand with 12 o'clock

• Calculate the angle made by the minute hand with 12 o'clock

• Find the difference between the two angles

• If the difference is greater than 180 degrees, subtract it from 360 degrees

• The result is the angle between the hour and minute hand

Printing all the subsequences in an array with a given sum.

• Use recursion to generate all possible subsequences.

• Check if the sum of each subsequence is equal to the given sum.

• Print the subsequences that satisfy the condition.

• Time complexity: O(2^n).

Sort an array of 0s and 1s in one loop using two pointers.

• Use two pointers, one starting from the beginning and the other from the end.

• Swap the values at the pointers if the value at the beginning pointer is greater than the value at the end pointer.

• Continue until the pointers meet in the middle.

• Time complexity is O(n).

The question is about finding the occurrence of characters in a string.

• Iterate through the string and count the occurrence of each character.

• Use a hash table to store the count of each character.

• Consider the case sensitivity of the characters.

• Handle special characters and spaces as required.

Find minimum number of coins to make a given value using dynamic programming.

• Use dynamic programming to find the minimum number of coins needed.

• Create a dp array to store the minimum number of coins for each value up to the given value.

• Iterate through each coin denomination and update the dp array accordingly.

• Return the value at the given value index in the dp array.

Find the first non-repeating character in a string.

• Create a hash table to store character frequency

• Iterate through the string and update the hash table

• Iterate through the string again and return the first character with frequency 1

Find the longest substring that is a palindrome in a given string.

• Use dynamic programming to solve the problem efficiently.

• Create a 2D boolean array to store the results of subproblems.

• Check for palindromes of length 1 and 2 separately.

• For substrings of length greater than 2, check if the first and last characters are the same and the substring between them is also a palindrome.

• Update the result if a longer palindrome is found.

Find the second maximum number in an array of strings.

• Convert the array of strings to an array of integers.

• Sort the array in descending order.

• Return the second element in the sorted array.

A prime number is a number greater than 1 that is divisible only by 1 and itself.

• Start with a loop to iterate through numbers

• Check if each number is divisible by any number from 2 to its square root

• If not divisible, add it to the list of prime numbers