Logical Interview Questions and Answers

Logic-based interview puzzles are becoming increasingly popular in recruitment processes to help employers find the brightest candidates and gain insight into a candidate’s thought process.

1. Find FaboconiSeries?

public static void FaboconiSeries()
{
int n=10;
int a=0;
int b=1;
System.out.println(a+","+b);
for(int i=0;i<n;i++)
{
int c=a+b;
a=b;
b=c;
System.out.println(c+".................FaboconiSeries");
}
}

2. Find ArmstrogNumber?

public void ArmstrogNumber()
{
int n=153;
int temp=n;

int sum=0;
while(temp!=0)
{
int a=temp%10;
sum=sum+a*a*a;
temp=temp/10;
}
if(sum==n)
{
System.out.println("yes................ArmstrogNumber");
}
}

3. Find Factorial?

public void Factorial()
{
int n=5;
int a=1;
for(int i=1;i<=n;i++)
{System.out.println(a+","+i);
a=a*i;
System.out.println(a+","+i);
}
System.out.println(a+".................Factorial");
}

4. Find Reversestring?

public void reversestring()
{
//using n
String s="akshay";
char[] ch=s.toCharArray();
for(int i=ch.length-1;i>=0;i--)
{
System.out.print(ch[i]);
}

//using n/2

String s1="akshay";
char[] ch1=s1.toCharArray();
for(int i=0;i<=ch1.length/2;i++)
{
char temp=ch1[i];
ch1[i]=ch1[ch1.length-i-1];
ch1[ch1.length-i-1]=temp;
}
System.out.println(Arrays.toString(ch1));
}

5. Find using recursion reverse?

//using recursion reverse
public static String stringreverse(String str)
{
String s1="a";
String s2="a";
if(s1.equals(s2))
{
System.out.println("true");
}
if(str.isEmpty())
{
return str;

}
return stringreverse(str.substring(1))+str.charAt(0);
}

6. Find Occurance Of Array?

public void occurance()
{
int[] array= {1,2,3,1,4,1,1,2,3,4,5,5,4};

HashSet<Integer> hs = new HashSet<>();
for(int i=0;i<array.length;i++) {
hs.add(array[i]);
}

for(int c:hs)
{
int count=0;
for(int j=0;j<array.length;j++)
{
if(c==array[j])
{
count++;
}
}
System.out.println(c+"occurance is:=="+count);
}
}
}

#Common Class And Main Method For Calling All Methods Above.

import java.util.Arrays;
import java.util.HashSet;

abstract public class Logical
{
public static void main(String[] args)
{
   Logical l=new Logical();
l.occurance(); // Calling Accurance
String t=l.stringreverse("akshay");
   System.out.println(t); //Calling Reverse String
   l.FaboconiSeries(); //Calling Faboconi Series
l.ArmstrogNumber(); //Calling Armstrong Number
l.Factorial(); //Calling Factorial
   l.reversestring(); //Calling Reverstring
Logical.FaboconiSeries();
}

7.occurance of string character.

import java.util.*;
public class HelloWorld
{
public static void main(String []args)
{
System.out.println("Hello World");
String str="abcdeabscderdscaaaaa";
char[] arr=str.toCharArray();
HashSet<Character> hs= new HashSet();
for(int i=0;i<arr.length;i++)
{
hs.add(arr[i]);
}
System.out.println(hs);
for(char set:hs)
{
int count=0;
for(int j=0;j<arr.length;j++)
{
if(set==arr[j])
count++;
}
System.out.println(set+"::occurance is:"+count);
}
}
}

8.The occurrence of number.

import java.util.*;
public class HelloWorld
{
public static void main(String []args){
System.out.println("Hello World");
int a[]={3,4,2,3,5,6,7,2,3,4,4,56};
HashSet<Integer> a1=new HashSet<Integer>();
for(int i=0;i<a.length;i++)
{
a1.add(a[i]);
}
System.out.println(a1);
for(int set:a1)
{ int count=0;

for(int j=0;j<a.length;j++)
{
if(set==a[j])
{
count++;
}
}
System.out.println(set+"occuerance is:"+count);
}
}
}

9.The occurrence of number by key.

import java.util.*;
public class HelloWorld
{
public static void main(String []args){
System.out.println("Hello World");
int a[]={3,4,2,3,5,6,7,2,3,4,4,56};
int x=5;
int count=0;
for(int i=0;i<a.length;i++)
{
if(x==a[i])
{
count++;
}
}
System.out.println("occurence is:"+count);
}
}

10.largest number.

//by using list.size()-1
import java.util.*;
public class HelloWorld
{
public static void main(String []args)
{
System.out.println("Hello World");
int[] a={11,23,34,56,76,78,33,12};
TreeSet<Integer> a1=new TreeSet<Integer>();
for(int i=0;i<a.length;i++)
{
a1.add(a[i]);
}
System.out.println(a1);
List<Integer> list= new ArrayList<Integer>(a1);
System.out.println(list.get(list.size()-1));
}
}

//method-2
import java.util.*;
public class HelloWorld
{
public static void main(String []args)
{
System.out.println("Hello World");
double[] numArray = {34,23,65,33,76,90,112,43};
double search = numArray[0];
for (int i=0;i<numArray.length;i++)
{
if(search < numArray[i])
search = numArray[i];
}
System.out.format("Largest element = %.2f", search);
}
}

11. Convert String to Int Without using ParseInt() Method.

public class StringToInteger
{
public static void main(String[] args)
{
int i = convertToInt("123679");
System.out.println("String decoded to number " + i);
}
public static int convertToInt(String input)
{
char[] ch=input.toCharArray();
int sum=0;
for(char c:ch)
{
sum=(sum*10)+(int)c -(int)'0';
}
return sum;
}
}

12.reverse String in Size/2.

public class ReverseString
{
public static void main(String[] args)
{
Scanner input=new Scanner(System.in);
System.out.println("Please enter String");
String str=input.nextLine();
char[] myarray=str.toCharArray();
int size=myarray.length;
char[] original=Arrays.copyOf(myarray, size);
for(int i=0;i<size/2;i++)
{
char temp= myarray[i];
myarray[i]=myarray[size-i-1];
myarray[size-i-1]=temp;
}
System.out.println("orignal array is:"+Arrays.toString(original));
System.out.println("reverse array is"+Arrays.toString(myarray));
}

}

13.Reverse string.

public class HelloWorld
{
public static void main(String []args){
String str="ashish";
char[] test=str.toCharArray();
for(int i=test.length-1;i>=0;i--)
{
System.out.println(test[i]);
}
}
}

14.Reverse Integer

import java.util.*;
public class HelloWorld
{
public static void main(String []args)
{
int a=4567896;
int reverse=0;
System.out.println("integer is:"+a);
while(a !=0)
{
reverse=reverse*10 +a%10;
a=a/10;
}
System.out.println("reverse is"+reverse);
}
}

15.Devide without Mod.

package org.ashish;
import java.util.*;
public class DivideWithoutMod
{
public static void main(String[] args)
{
Scanner input=new Scanner(System.in);
System.out.println("Enter Divident");
int divident=input.nextInt();
System.out.println("Enter Divisor");
int divisor=input.nextInt();
int Qoutient=0;
while(divident>=divisor)
{
divident=divident-divisor;
Qoutient++;

}
System.out.println("Remainder is:"+divident);
System.out.println("Qoutient is:"+Qoutient);
}
}

16.Ascending Order.

import java.util.Arrays;
public class HelloWorld
{
public static void main(String []args)
{
System.out.println("Hello World");
int numb=7;
int[]arr={4,2,1,6,7,5,3};
System.out.println("original array is:"+Arrays.toString(arr));
int temp;
for(int i=0;i<numb-1;i++)
{
for(int j=0;j<numb-i-1;j++)
{
if(arr[j]>arr[j+1])
{
temp=arr[j];
arr[j]=arr[j+1];
arr[j+1]=temp;
}
}
}
System.out.println("Sorted array is:"+Arrays.toString(arr));
}
}

17.Araay Union and Intersection by Hashing.

import java.util.HashSet;
// Java program to find union and intersection
// using Hashing
class Main
{
// Prints union of arr1[0..m-1] and arr2[0..n-1]
static void Union(int a[],int b[])
{
HashSet<Integer> hs= new HashSet<>();
for(int i=0;i<a.length;i++)
hs.add(a[i]);
for(int j=0;j<b.length;j++)
hs.add(b[j]);
System.out.println(hs);
}
static void Intersection(int a[],int b[])
{
HashSet<Integer> hs=new HashSet<>();
for(int i=0;i<a.length;i++)
hs.add(a[i]);
for(int j=0;j<b.length;j++)
if(hs.contains(b[j]))
System.out.println(b[j]+"");
}

// Prints intersection of arr1[0..m-1] and arr2[0..n-1]
// Driver method to test the above function
public static void main(String[] args)
{
int a[] = {7, 1, 5, 2, 3, 6};
int b[] = {3, 8, 6, 20, 7};
System.out.println("Union of two arrays is : ");
Union(a,b);
System.out.println("Intersection of two arrays is : ");
Intersection(a,b);
}
}

18.Iterator & List

Public class test
{
public static void main(String []args)
{
System.out.println("Hello World");
ArrayList<String> al = new ArrayList<String>(5);
al.add("ashish");
al.add("anita");
al.add("ashu");
al.add("suniti");
al.add("sandip");
al.add("sonal");
System.out.println("original Content of al is:");
Iterator it= al.iterator();
while(it.hasNext())
{
Object elem=it.next();
System.out.println("Name:"+elem);
}
ListIterator lit=al.listIterator();
while(lit.hasNext())
{
Object elem=lit.next();
lit.set(elem+"test");
System.out.println("after modification al is:");

it= al.iterator();
while(it.hasNext())
{
Object elem=it.next();
System.out.println("Name:"+elem);
}
while(lit.hasPrevious())
{
Object elem=lit.previous();
System.out.println(elem+"");
}
}
}

19.String anagram.

import java.util.*;
public class HelloWorld
{
public static void main(String []args){
System.out.println("Hello World");
boolean status=true;
String str="keep";
String str1="peek";
if(str.length()!=str1.length())
{
status=false;
}
else{
char[] chr=str.toLowerCase().toCharArray();
char[] chr1=str1.toLowerCase().toCharArray();
Arrays.sort(chr);
Arrays.sort(chr1);
status=Arrays.equals(chr,chr1);
}
if (status)
{
System.out.println(str + " and " + str1 + " are anagrams");
}
else{
System.out.println(str + " and " + str1 + " are not anagrams");
}
}
}

20. Mixed Array addition finds occurrence.

import java.util.*;
public class HelloWorld
{
public static void main(String []args){
System.out.println("Hello World");
int[] arr={1,2,3,-1,2,4,3,2};
int sum;
ArrayList list =new ArrayList();
for(int i=0;i<arr.length;i++)
{
for(int j=1+i;j<arr.length;j++)
{
sum=arr[i]+arr[j];
list.add(sum);
}
}
System.out.println(list);
int length=list.size();
HashSet<Integer> hs=new HashSet(list);
System.out.println(hs);
for(Object set:hs)
{
int count=0;
for(int i=0;i<length;i++)
{
if(set==list.get(i))
{
count++;
}
}
System.out.println(set+":occurance is:"+count);
}
}
}

21.LowerCase to UperCase and Upper to lower.

import java.util.*;

public class HelloWorld{
public static void main(String []args)

{

System.out.println("Hello World");

StringBuffer str= new StringBuffer("KeepReady");

convertOpposite(str);

System.out.println(str);

}

public static void convertOpposite(StringBuffer str)

{

for(int i=0;i<str.length();i++)

{

Character c=str.charAt(i);

if(Character.isLowerCase(c))

{

str.replace(i, i+1, Character.toUpperCase(c)+"");
}

else{

str.replace(i, i+1, Character.toLowerCase(c)+"");

}

}
}

22.String Length without length method.

public class Main

{

public static void main(String[] args)
{

System.out.println("Hello World");

String str="abcde";

int count=0;

for(char c:str.toCharArray())

{

count++;

}

System.out.println(count);
}
}

23. Write Custom Exception .

class myException extends Exception
{

myException(String s)
{

super(s);

}

public class Main

{

static void validate(int age) throws myException

{

if(age<18)

{

throw new myException("under age need id proof");

}

else{

throw new myException("above 18 ok");

}
public static void main(String[] args)
{

System.out.println("Hello World");

try{

validate(19);

}

catch(Exception e)

{

System.out.println(e);

}

24.Custom_Thread.

1.By implementing Runnable Interface:

public class Main implements Runnable

{

public void run()
{

System.out.println("thread running");

}

public static void main(String[] args)
{
System.out.println("Hello World");

Main m = new Main();

Thread t= new Thread(m);

t.start();
}
}

2.By extending Thread Class:

public class Main extends Thread

{

public void run(){

System.out.println("thread running");

}

public static void main(String[] args) {

System.out.println("Hello World");

Main m = new Main();

m.start();

}

24.Write MVC configuration-XML based

1.Dispatcher Servlet configuration(web.xml)

<servlet-name>Spring</servlet-name>

<servlet-class> org.springframework.web.servlet.DispatcherServlet</servlet-class>

</servlet>

<servlet-mapping>

<servlet-name>spring</servlet-name>

<url-pattern>/</url-pattern>

</servlet-mapping>

2.Spring web configuration File(Spring-servlet.xml)

<beans>

<context:component-scan base-package = "com.tutorialspoint" />

</bean>
<bean>

<bean>

</beans>

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