The Array Height Checker Problem in Java
The challenge
Students are asked to stand in non-decreasing order of heights for an annual photo.
Return the minimum number of students that must move …
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342 articles about java development, tools, and best practices
Find the Squares of a Sorted Array in Java
The challenge
Given an array of integers A sorted in non-decreasing order, return an array of the squares of each number, also in sorted …
Sorting a Java Array by Parity
The challenge
Given an array A of non-negative integers, return an array consisting of all the even elements of A, followed by all the odd elements of …
Remove Duplicates from Sorted Array in Java
Say you have an array of primitive integers and you want to remove all duplicates.
You can find out how many non-duplicate integers are in the array …
Read Article →Replace Elements with Greatest Element on Right Side using Java
The challenge
Given an array arr, replace every element in that array with the greatest element among the elements to its right, and replace the last …
The Valid Mountain Array Problem using Java
Introducing the problem
Given an array A of integers, return true if and only if it is a valid mountain array.
Recall that A is a mountain array if …
Read Article →Find Numbers with Even Number of Digits using Java
The challenge
Given an array nums of integers, return how many of them contain an even number of digits.
Example 1:
Example 2:
Constraints:
1 …
How to use a Java HashSet by example
What is a HashSet
A HashSet is an unordered collection containing unique elements. It has the standard collection operations Add, Remove, Contains, …
The Decoded String at Index using Java
The Challenge
An encoded string S is given. To find and write the decoded string to a tape, the encoded string is read one character at a time and …
Find the Minimum Absolute Difference in BST using Java
The question
Given a binary search tree with non-negative values, find the minimum absolute difference between values of any two nodes.
Example: …
Read Article →Find Maximum Subarrays using Java
The problem
Given an integer array nums, find the contiguous subarray (containing at least one number) which has the largest sum and return its sum. …
Finding Number Complements using Java
The problem
Given a positive integer num, output its complement number. The complement strategy is to flip the bits of its binary representation. …