Factorial of Number

    package com.nataraja.b;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Fact {
public static void main(String[] args) throws NumberFormatException, IOException {
 System.out.println("Enter a Number:");
 BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
 int n=Integer.parseInt(br.readLine());
 
 int f=fact(n);
 System.out.println(f);
}

public static int fact(int n){
 if(n==0)
  return 1;
 else
  return fact(n-1)*n;
}
}

  

Array-1

Enter a Length of array:
5
2
1
5
0
6
Array Element to Number:21506
Enter a value to add number:
4
Array value after adding:
[2][1][5][1][0]
===================

package com.nataraja.b;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class ElementToNumber {
 public static void main(String[] args) throws IOException {
  int array[];
  BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
  System.out.println("Enter a Length of array:");
  int n=Integer.parseInt(br.readLine());
  array=new int[n];
  for(int i=0;i=0;i--){
   System.out.print("["+res[i]+"]");
  }
  
 }
}

Flyod's Algorithm

1 
23 
456 

78910 
====================

  
  public static void main(String[] args) {
    int n=10,k=1;
    for(int i=1;i<=n;i++){
      for(int j=2;j<=i;j++){
        System.out.print(k);
        k++;
      }
      System.out.println(" ");
    }
  }

Sum of integers in the string

package com.nataraja.b;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class SumOfNumberInString {
 public static void main(String[] args) throws IOException {
  BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
  System.out.println("Enter a String:");
  String s=br.readLine();
  removeChar(s);
}
 
 public static void removeChar(String s){
  StringBuffer res=new StringBuffer();
  for(int i=0;i='0'&&s.charAt(i)<='9')){
    res.append(s.charAt(i));
   }
  }
  
  int n=Integer.parseInt(res.toString()),r=0,sum=0;
  
  while(n!=0){
   r=n%10;
   sum+=r;
   n=n/10;
  }
  System.out.println("Sum of  numbers in the string:"+sum);
 }
}

Find String Length without using length()

package com.nataraja.b;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class StringLength {
public static void main(String[] args) throws IOException {
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter a String:");
String s=br.readLine();

int i=0;

try{
while(true){
s.charAt(i);
i++;
}
}catch(Exception e){
System.out.println(i);
}
}

}

Second Largest element in the array

Enter a Array Size:
6
Enter a Array Value:
2
5
3
8
2
6
Descending order:
8
6
5
3
2
Second Largest Element:6

======================


package com.nataraja.b;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.HashSet;
import java.util.Iterator;

public class SecondLargest {
public static void main(String[] args) throws NumberFormatException, IOException {
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter a Array Size:");
int n=Integer.parseInt(br.readLine());
int a[]=new int[n];
int newArray[]=new int[n];

System.out.println("Enter a Array Value:");
for(int i=0;i<n;i++){
a[i]=Integer.parseInt(br.readLine());
}
HashSet hs=new HashSet();
for(int i=0;i<n;i++){
hs.add(a[i]);
}
newArray=new int[hs.size()];
Iterator it=hs.iterator();
int k=0;
while(it.hasNext()){
newArray[k++]=(int) it.next();
}

for(int i=0;i<hs.size();i++){
for(int j=i+1;j<hs.size();j++)
if(newArray[i]<newArray[j]){
int t=newArray[i];
newArray[i]=newArray[j];
newArray[j]=t;
}
}
System.out.println("Descending order:");
for(int i=0;i<newArray.length;i++){
System.out.println(newArray[i]);
}
System.out.println("Second Largest Element:"+newArray[1]);
}
}

String-3

Enter a String:
Hi Iam Nataraja B
Reverse String:B ajarataN maI iH

Reversed word of string:B Nataraja Iam Hi

=======================================

package com.nataraja.b;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class ReverseWord {
public static void main(String[] args) throws IOException {
System.out.println("Enter a String:");
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
String s=br.readLine();
StringBuffer sb=new StringBuffer();
StringBuffer res=new StringBuffer();
s=reverseString(s);
System.out.println("Reverse String:"+s);
for(int i=0;i<s.length();i++){
if(s.charAt(i)!=' '&& i!=s.length()){
sb.append(s.charAt(i));
}else{

res.append(reverseWord(sb).toString()+" ");
sb=new StringBuffer();

}
}
res.append(reverseWord(sb).toString());
System.out.println("Reversed word of string:"+res.toString());
}

public static String reverseWord(StringBuffer sbf){
String s="";
for(int i=sbf.length()-1;i>=0;i--){
s+=sbf.charAt(i);
}
return s;
}

public static String reverseString(String sbf){
StringBuffer rev=new StringBuffer(sbf);
rev.reverse();
return rev.toString();
}
}

Reverse String without in built method

package com.nataraja.b;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class ReverseString {

public static void main(String[] args) throws IOException {
System.out.println("Enter a Number:");
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
String s=br.readLine();
StringBuffer sb=new StringBuffer();
for(int i=s.length()-1;i>=0;i--){
sb.append(s.charAt(i));
}
System.out.println(sb);
}
}

String Example-1

Enter a String:
Nataraja123b? {b"
String without number & special character:Natarajabb
String without number:Natarajab? {b"

String without character:123

===========================================

package com.nataraja.b;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class RemoveNumber {
public static void main(String[] args) throws IOException {
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter a String:");
String s=br.readLine();
removeNumberSpecialChar(s);
removeNumber(s);
removeChar(s);
}

public static void removeNumberSpecialChar(String s){
StringBuffer res=new StringBuffer();
for(int i=0;i<s.length();i++){
if(s.charAt(i)>='a'&&s.charAt(i)<='z'||s.charAt(i)>='A'&&s.charAt(i)<='Z'){
res.append(s.charAt(i));
}
}
System.out.println("String without number & special character:"+res.toString());
}

public static void removeNumber(String s){
StringBuffer res=new StringBuffer();
for(int i=0;i<s.length();i++){
if(!(s.charAt(i)>='0'&&s.charAt(i)<='9')){
res.append(s.charAt(i));
}
}
System.out.println("String without number:"+res.toString());
}

public static void removeChar(String s){
StringBuffer res=new StringBuffer();
for(int i=0;i<s.length();i++){
if((s.charAt(i)>='0'&&s.charAt(i)<='9')){
res.append(s.charAt(i));
}
}
System.out.println("String without character:"+res.toString());
}
}

Find Reaminder of Number without using "%" operator

package com.nataraja.b;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Remainder {

public static void main(String[] args) throws NumberFormatException, IOException {

BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter a number:");
int n=Integer.parseInt(br.readLine());
System.out.println("Enter a devidend");
int m=Integer.parseInt(br.readLine());
System.out.println("Remainder:"+remainder(m,n));
}

public static int remainder(int m,int n){
int res=0; 
for(int i=1;i<=n/m;i++){
res=i*m;
}
return n-res;
}
}

Pattern-3

Write a Program to display below Pattern?

Enter a Number:
5
***** 
 **** 
  *** 
   ** 
    *

====================================

package com.nataraja.b;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Pattern3 {
public static void main(String[] args) throws NumberFormatException, IOException {
System.out.println("Enter a Number:");
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
int n=Integer.parseInt(br.readLine());
for(int i=1;i<=n;i++){
for(int j=1;j<=n;j++){
if(j>=i)
System.out.print("*");
else
System.out.print("  ");
}
System.out.println(" ");
}
}
}

Remove Duplicate Elements from Array

Enter a Array Size:
5
Enter a Array Value:
2
1
3
2
3
Array without Duplicate Elements
1
2
3

=======================

package com.nataraja.b;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.Iterator;

public class ArrayDuplicate {

public static void main(String[] args) throws NumberFormatException, IOException {
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter a Array Size:");
int n=Integer.parseInt(br.readLine());
int a[]=new int[n];

System.out.println("Enter a Array Value:");
for(int i=0;i<n;i++){
a[i]=Integer.parseInt(br.readLine());
}
HashSet hs=new HashSet();
for(int i=0;i<a.length;i++){
hs.add(a[i]);
}

System.out.println("Array without Duplicate Elements");
Iterator<E> it=hs.iterator();
while(it.hasNext()){
System.out.println(it.next());
}
}

}

Count number of time Digit Repeats

Count the Number of  time the Digit Repeats

Example:

from 1 to 20 the digit 2 repeats 11 times..

==============================

package com.nataraja.b;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class CountDigitRepeat {
public static void main(String[] args) throws NumberFormatException, IOException {
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter a number:");
int n=Integer.parseInt(br.readLine());
System.out.println("Enter a Limit:");
int m=Integer.parseInt(br.readLine());
int c=findDigit(n,m);
System.out.println("Count:"+c);
}

public static int findDigit(int n,int m){
int c=0;
for(int i=1;i<=m;i++){
int t=i,r;
while(t!=0){
r=t%10;
t=t/10;
if(r==n){
c++;
t=0;
}
}
}
return c;
}
}

Pattern-2

Mostly asked Programming Interview Questions:

Write a Program to display below Pattern?


**********
**            **
*  *        *  *
*    *    *    *
*      **      *
*      **      *
*    *    *    *
*  *        *  *
**            **
**********

=======================
package com.nataraja.b;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Pattern2 {

public static void main(String[] args) throws  IOException {
System.out.println("Enter a Number:");
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
int  n;
try{
n=Integer.parseInt(br.readLine());
int t=n;
int k=1;
for(int i=1;i<=n;i++){
for(int j=1;j<=n;j++){
if(j==1||j==n||i==1||i==n||t==j||j==k){
System.out.print("*");
}else{
System.out.print("  ");
}
}
t--;
k++;
System.out.println(" ");
}
}catch(Exception e){
//e.printStackTrace();
}

}
}

Pattern-1

Write a Program to display below Pattern?

****
***
**
*

===================

package com.nataraja.b;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Pattern1 {

public static void main(String[] args) throws NumberFormatException, IOException {
System.out.println("Enter a Number:");
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
int n=Integer.parseInt(br.readLine());
for(int i=1;i<=n;i++){
for(int j=1;j<=n-i;j++){
System.out.print("*");
}
System.out.println(" ");
}
}
}