Winsen SDE-1 Interview Experience (2024)

import java.util.*;



public class winsen {







    /* T : n^2 S: O(1)    2, 3, 5, 7, */

    public static int  countPrime(int n){

        int count=0;



        for ( int i=2; i<=n; i++){

            if( isPrime(i)) count++;

        }



        return count;



    }



    public static boolean isPrime(int n){

        if( n<2) return  true;



        for( int i=2; i<n ; i++){

            if( n%i==0) return false;

        }

        return  true;

    }









    /*

    *  2, 4, 6, 8

    *  3, 6, 9,

    *  4, 8,

    *  5, 10

    *

    * */

    public static int  countPrimeSteveOfEreross(int n){

         int[] arr = new int[n+1];



        Arrays.fill(arr, 1);



        arr[0]=0;

        arr[1]=0;



        for( int i=2; i<=n; i++){  // O(n)

            int   j=2;

            while ( i*j <= n){  // O(n) ...  O(n^2)

                arr[i*j]=0;

                j++;

            }

        }



        int primeCount=0;

        for(int i: arr) primeCount+=i;

        return  primeCount;

    }





    /*

    *

    * Input: s = "abpcplea",

    * dictionary = ["ale","apple","monkey","plea"]   --> []

      Output: "apple"



       Input: s = "abpcplea", dictionary = ["a","b","c"]

       Output: "a"

    *

    *

    *     T : O (n log(N) ). +   M*N*K

    *

    *

    *

    * */



    public static String lexSmallStringByRemovingSomeCharsFromString( String str, String[] dict){



        List<String>  possibleStrings= new ArrayList<>();

        for( String s : dict){            // T : O(len(dict))

            if( isPossible( str, s)) possibleStrings.add(s);

        }



        if (possibleStrings.isEmpty()) return  "";



        Collections.sort(possibleStrings , (a,b) ->  ( b.length()-a.length())  );  // T : O(nlog(n))



       System.out.println(possibleStrings);



        return  possibleStrings.stream()

                .filter(  strr -> strr.length()==possibleStrings.get(0).length())

                .sorted().findFirst().orElse("");  // T : O(nlog(n))

    }



    public  static  boolean isPossible( String str, String s){

        int m = str.length(), n= s.length(), i=0, j=0;



        while (i<m && j<n){

            if( str.charAt(i) == s.charAt(j)){    // T : O(max(m,n))

              i++;

              j++;

            }else  i++;

        }



      return j == n;



    }





    /**

    *  what is interface?

     * what is difference between hashmap & concurrent hashmap

     * what is functional interface

     * what is SOLID principles

     * what are Design patterns

     * what are error handling methods

     * what is method overloading & overriding

     * what is abstraction & encapsulation

     * what is horizontal scaling & vertical scaling

     * how to make a class immutable

     * what are immutable classes other than String, all wrapper class are immutable for example. Integer, Double,Float, Character etc..

    * */

    }