leetcode- Rotate Image

Leetcode: https://leetcode.com/problems/rotate-image/description/ Given input matrix = [1,2,3], [4,5,6], [7,8,9] rotate the input matrix in-place such that it becomes: [7,4,1], [8,5,2], [9,6,3] (x, y), the affected point is (y, n – x – 1), (n – x – 1, n – y – 1), (n – y – 1, x),  “n” is the size of the matrix. … Continue reading leetcode- Rotate Image

LeetCode – Plus One

Given a non-negative integer represented as a non-empty array of digits, plus one to the integer. You may assume the integer do not contain any leading zero, except the number 0 itself. The digits are stored such that the most significant digit is at the head of the list. For example: Q1. int[] nums = {1,2,3,4}; int[] … Continue reading LeetCode – Plus One

How to check if a string has all unique characters

GitHub:  solution 1.1 Check if the string is an ASCII string. There are many different solutions, I practiced with a HashSet. Time complexity: O (n). from Cracking the Code Interview , isUniqueChars2 is an insteresting solution. A good source to explain the solution: trying to understand: checker |= (1 << val) Reference: http://javahungry.blogspot.com/2014/11/string-has-all-unique-characters-java-example.html https://www.codeproject.com/Articles/760162/How-to-check-if-a-string-has-all-unique-characters

Array Implementation of Queue (Fixed size)

github:arrayQueue.java.  Purpose: reuse a fixed size array. ----> Tracking 2 variables frontIndex for deletion and rearIndex for insertion. CheckPoint: array size > 0. isEmpty() Check rearIndex == frontIndex. Enqueue --> queue is full. Dequeue --> queue is empty. Complexity Analysis: Time complexity : enqueue: O(1) assign the value to array[rearIndex] dequeue: O(1) move frontIndex to next … Continue reading Array Implementation of Queue (Fixed size)