Grouping of Anagrams
Objective: Given an array of strings, write an algorithm to group the anagrams. Example: Input: [rat, art, cat, act, dog, god, tar, pat] Output: [rat, art, tar] [cat, act] [pat] [dog, god] Approach: If...
Tagged: Intermediate
Print Processes and its messages from a given log file
Problem Statement: There is an application that has several processes running in parallel and each process prints the logs in a single log file. Log message contains the process name, timestamp, message type (WARN,...
Sieve of Eratosthenes – Find all Prime Numbers less than equal to N | Set 2
Objective: Given a number N, Write a program to find all prime numbers which are between 0 and N using Sieve of Eratosthenes algorithm. Prime Number: A prime number is a natural number that...
Convert Postfix to Infix Expression
Objective: Given a Postfix expression, write an algorithm to convert it into Infix expression. Example: Input: Postfix expression: A B + Output: Infix expression- (A + B) Input: Postfix expression: ABC/-AK/L-* Output: Infix expression:...
Longest substring with at most two unique characters
Objective: Given a string, write an algorithm to find the longest substring with at most two characters. Example: Input: aabbccddc Output: ccddc, length: 5 Input: aabacbeeeebeaabb Output: beeeebe, length 7 Input: aaaaaa Output: Only...
Monotone Increasing Digits
Objective: Given a number N, find the largest number which is less than equal to N and has monotone increasing digits. Monotone Increasing Digits – If all the pairs (x, y) of adjacent digits...
Convert Prefix to Infix Expression
Objective: Given a Prefix expression, write an algorithm to convert it into Infix expression. Example: Input: Prefix expression: + A B Output: Infix expression- (A + B) Input: Prefix expression: *-A/BC-/AKL Output: Infix expression:...
Convert Infix to Prefix Expression
Objective: Given an Infix expression, write an algorithm to convert it into Prefix expression. Example: Input: Infix expression – A + B Output: Prefix expression- +AB Input: Infix expression – A+B*(C^D-E) Output: Prefix expression-...
Convert Infix to Postfix Expression
Objective: Given an Infix expression, write an algorithm to convert it into Postfix expression. Example: Input: Infix expression – A + B Output: Postfix expression- AB+ Input: Infix expression – A+B*(C^D-E) Output: Postfix expression-...
Evaluation of Infix expressions
Infix notation is commonly used in arithmetic formula or statements, the operators are written in-between their operands. Let’s assume the below Operands are real numbers. Permitted operators: +,-, *, /, ^(exponentiation) Blanks are permitted...
Valid Multiple Parentheses
Objective: Given a string containing just the characters ‘(‘, ‘)’, ‘{‘, ‘}’, ‘[‘ and ‘]’, determine if the input string is valid. Example: ()()([]({}))[] valid: true ()({]) valid: false []{}() valid: true [(}{)] valid: false Earlier we had seen problem Valid...
Generate all the strings of length n from 0 to k-1.
Objective: Given two numbers, n and k (k>=n), write an algorithm to generate all the strings of length n drawn from 0 – k-1. Example: k = 2, n = 2Output: 0 0 0...
Find Number of reverse pairs in an array
Objective: Given an array of integers A[],find no of reverse pairs means no of (i, j) pairs where i < j and A[i]>A[j]. Example: A[] = {10, 3, 4, 2, 5, 7, 9, 11}...
Heap Sort – Java Implementation
What is Heap Sort?? Heap sort is comparison based sorting algorithm. Heap sort is considered as improved selection sort, it divides the input into sorted and unsorted region. The improvement from selection sort is...
Get the Sum of Digits in a number till it become a single digit
Objective – Given a number, Write a program to get the sum of digits in a number till it become a single digit. Example: N = 999 -> 9+9+9 = 27-> 2+7 = 9...