# Category: Numbers

## Numbers with prime set bits in a given range using Sieve of Eratosthenes Algorithm

Objective: Given a range, find all the numbers in the range which has prime set bits using Sieve of Eratosthenes Algorithm. Earlier we had seen a similar problem -Numbers with prime set bits in...

## Hamming Distance between two given integers

Objective: Given two integers, write an algorithm to calculate the hamming distance between the integers.  Hamming Distance: Hamming distance between two integers is the number of positions at which the bits are different. Example:...

## Find all the Armstrong numbers in the given range

Objective: Given a range of integers, wrote a program to find all the Armstrong numbers in that range. What is Armstrong number: Determine the number of digits in the number. Call that n. Then...

## Collatz Conjecture – Maximum Steps takes to transform (1, N) to 1.

Objective: Given a number N, write an algorithm to find the maximum number of steps it takes to transform (1, N) to 1 using Collatz Conjecture.  The Collatz conjecture is a conjecture in mathematics...

## Find all unique combinations of exact K numbers (from 1 to 9 ) with sum to N

Objective: Given two integers N and K. Write an algorithm to find all the combinations of k numbers which sum to N.  Conditions:  All K numbers must be between 1 and 9 and unique....

## Check if Number is divisible by its digits

Objective: Given a number, write a program to check if the number is divisible by all of its digits separately. Example: N = 15 Output: true (15 is divisible by 1 and 5) N...

## Check if the given number is Armstrong number or not

Objective: Given a number, write a program to find out whether the number is Armstrong number or not What is Armstrong number: Determine the number of digits in the number. Call that n. Then...

## Evaluation of Prefix Expressions (Polish Notation) | Set 1

Prefix notation is a notation for writing arithmetic expressions in which the operands appear after their operators. There are no precedence rules to learn. Let’s assume the below Operands are real numbers in real...

## Evaluation of Postfix Expressions (Polish Postfix notation) | Set 2

Earlier we had discussed how to evaluate postfix expressions where operands are of single-digit. In this article, we will discuss how to evaluate postfix expressions for any number ( not necessarily single digit.) Postfix...

## Evaluation of Postfix Expressions (Polish Postfix notation) | Set 1

Postfix notation is a notation for writing arithmetic expressions in which the operands appear before their operators. There are no precedence rules to learn, and parentheses are never needed. Because of this simplicity. Let’s...

## Find all the numbers in the range which has prime set bits.

Objective: Given a range, find all the numbers in the range which has prime set bits. Example: L = 4, R = 10 Output: 5 Explanation: 4 = 1 0 0 ( not prime)...

## Smallest Number after Removing K digits

Objective: Given a number with N digits, write a program to get the smallest number possible after removing k digits from number N. OR Implement a method that returns the lowest possible number that...

## Find the maximum number present in a String

Given a string with alphabets and numbers. Write an algorithm to find the maximum number in the string. If any number is greater than equal to Max_Value of integer then return the Max_Value. Example:...

## Convert Prefix to Postfix Expression

Objective: Given a Prefix expression, write an algorithm to convert it into Postfix expression. Example: Input: Prefix expression:  + A B  Output: Postfix expression: A B + Input: Prefix expression:  *-A/BC-/AKL Output: Postfix expression:...

## Convert Roman Number to Integer

Objective: Given a Roman number, write a program to convert it to Integer. Roman Number –   Letters used in Roman numerals and the corresponding numerical values are given in the table below. Rules: ...