Concepts of Computer Science

when someone starts a career in software engineering there are plenty of options. Although most graduates have the same degree, everyone starts in a different role. Developer / Coder - Engineers in this role get a chance to actually implement and write software. At the start of a career mostly it is about fixing defects in existing software then taking small changes to the software and eventually getting to the point to handle and implement more complex changes.  Quality analysts / Quality engineers - Engineers in this role test and automate software. This is a challenging role where one has to know about the full functionality of the software and test accurately so the software built is of high quality. This role also involves the automation of test cases and preparing a test suite that can be run and detect issues automatically. Release Engineers - Once the software is built and tested release engineers are responsible for pushing a set of code to production. A production is a plac

Here is a list of some of the best questions asked in interviews:-  Must do 75 https://leetcode.com/list/5hkn6wze/ Must do 60  https://leetcode.com/list/5eie1aqd/ Must do medium:-  https://leetcode.com/list/5xaelz7g/ Must do Easy:-   https://leetcode.com/list/5r7rxpr1/ Graph:-  https://leetcode.com/list/x18ervrd/  Dynamic Programming:-    https://leetcode.com/list/x14z0dxr/  FaceBook interviews:- https://leetcode.com/list/xyu98pv6/  Amazon Interviews:-  https://leetcode.com/list/5hkniyf7/  Google Interviews:- https://leetcode.com/list/xyu9xfo1/ https://github.com/nazarmubeen/TopProblems/blob/master/README.md

  A message containing letters from   A-Z   is being encoded to numbers using the following mapping: 'A' -> 1 'B' -> 2 ... 'Z' -> 26 Given a  non-empty  string containing only digits, determine the total number of ways to decode it. Example 1: Input: "12" Output: 2 Explanation:  It could be decoded as "AB" (1 2) or "L" (12). Example 2: Input: "226" Output: 3 Explanation:  It could be decoded as "BZ" (2 26), "VF" (22 6), or "BBF" (2 2 6). class Solution { public int numDecodings(String s) { int ways=0; ways=countDecoding(s.toCharArray(),s.length()); return ways; } int countDecoding(char[] digits, int n){ // System.out.println(" digits "+disgits[0]); // for base condition "01123" should return 0 // base cases if (n == 0 || (n == 1 && digits[0]!='

  Given two words  word1  and  word2 , find the minimum number of operations required to convert  word1  to  word2 . You have the following 3 operations permitted on a word: Insert a character Delete a character Replace a character Example 1: Input: word1 = "horse", word2 = "ros" Output: 3 Explanation: horse -> rorse (replace 'h' with 'r') rorse -> rose (remove 'r') rose -> ros (remove 'e') Solution:- class Solution { public int minDistance(String word1, String word2) { if(word1.length()==0){ return word2.length(); } if(word2.length()==0){ return word1.length(); } if(word1.length()==0 && word2.length()==0){ return 0; } int[][] result=new int[word1.length()+1][word2.length()+1]; for(int i=0;i<=word1.length();i++){ result[i][0]=i; }

   https://leetcode.com/problems/two-sum/ Given an array of integers  nums  and an integer  target , return  indices of the two numbers such that they add up to  target . You may assume that each input would have  exactly  one solution , and you may not use the  same  element twice. You can return the answer in any order.   Example 1: Input: nums = [2,7,11,15], target = 9 Output: [0,1] Output: Because nums[0] + nums[1] == 9, we return [0, 1]. Example 2: Input: nums = [3,2,4], target = 6 Output: [1,2] Example 3: Input: nums = [3,3], target = 6 Output: [0,1] class Solution {     public int[] twoSum(int[] nums, int target) {              HashMap<Integer,Integer> map=new HashMap<Integer,Integer>();                  for(int i=0;i<nums.length;i++){                          if(map.get(nums[i])==null){                 map.put(target-nums[i],i);             }             else{                 return new int[]{map.get(nums[i]),i};             }         }         return null