Count Set bits in a given Number
Objective: Given a Number, find all the set bits in that number. Example: Number: 23 Set bits: 4 (10111) Number: 15 Set bits: 4 (1111) Number: 21 Set bits: 3 (10101) Approach: Check the...
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Product of all Unique elements in a given array.
Objective: Given an array of integers which contains duplicates as well. Write a program to find the product of all unique elements in the array. This problem is also referred as find the product...
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...
Check if given number is perfect square – O(√N) Solution
Objective: Given a number, write a program to check if given number is perfect sqaure. Example: N = 16 Output: True N = 32 Output: False Approach: Naive Approach: If N = 1 return...
Find first three largest elements in a given array
Objective: Given an array of integers, write an algorithm to find the first three largest elements in the array. Example: Int [] a = { 6, 8, 1, 9, 2, 1, 10}; Output: 10,...
Valid Brackets – Part 2 | Stack Method
Objective: Given a string containing just the characters ( , ) determine if the input string is valid. Example: ()()(()(()))() valid: true )()()( valid: false ()()) valid: false Approach: Earlier we discussed the solution which keeps...
Find two smallest elements in a given array
Objective: Given an array of integers, write an algorithm to find the two smallest elements in the array. Example: Int [] a = { 6, 8, 1, 9, 2, 10}; Output: 1, 2 Int...
Print all Unique elements in a given array
Objective: Given an array of integers which contains duplicates as well. Write a program to print all unique elements in the array. This problem is also referred as print all distinct elements in the...
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}...
Find first two largest elements in a given array
Objective: Given an array of integers, write an algorithm to find the first two largest elements in the array. Example: Int [] a = { 6, 8, 1, 9, 2, 1, 10}; Output: 10,...
Calculate Logn base r – Java Implementation
Objective: Given a number n and r, write a program to calculate Logrn Example: N = 32, r =2 Log232= 5 N = 64, r = 4 Log464= 3 Approach: Without using built-In function-...
Dijkstra Algorithm Implementation – TreeSet and Pair Class
Earlier we have seen what Dijkstra algorithm is is and how it works. In this article we will see its implementation using adjacency list and TreeSet. Example: Implementation – Adjacency List and Priority Queue...
Check if Given Number is power of 2.
Objective: Given a number, write a program to find if number is power of two. Example: N = 5 Output: false. N = 8 Output: true (23) N = 512 Output: true (29) Approach:...
Rotate the given array in cycles
Objective: Given an array of integers, write a program to rotate the array in cyclic manner by one. Example: Int a [] = {1, 2, 3, 4, 5} Output: {2, 3, 4, 5, 1}...
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...