Java Programming Examples
Armstrong Number:
import java.util.Arrays;import java.util.Random;public class QuickSortTest {/*** @param args*/static int[] arr = new int[20];public static void main(String[] args) {// TODO Auto-generated method stubRandom gen = new Random();for(int i=0; i<arr.length ;i++){arr[i] = gen.nextInt(20);System.out.println(arr[i]);}sort(0,arr.length-1);System.out.println("Sorted" + Arrays.toString(arr));}private static void sort(int low, int high) {// TODO Auto-generated method stubint i = low;int j = high;int pivot = arr[low + (high-low)/2];while(i<=j){while(arr[i]<pivot){i++;}while(arr[j]>pivot){j--;}if(i<=j){exchange(i,j);i++;j--;}}if(low<j){sort(low,j);}if(i<high){sort(i,high);}}private static void exchange(int i, int j) {// TODO Auto-generated method stubint temp = arr[i];arr[i]=arr[j];arr[j]= temp;}}
public class Factorial {/*** @param args*/public static void main(String[] args) {// TODO Auto-generated method stubSystem.out.println("factorial of 5 = " + fact(5) );}public static int fact(int num){if(num ==0 || num==1){return num;}else{return num*fact(num-1);}}}
public class Fib {/*** @param args*/public static void main(String[] args) {// TODO Auto-generated method stubint num = 8;for(int i =0;i<num;i++)System.out.println(fibo(i));}public static int fibo(int n){if(n==0|n==1) return n;elsereturn fibo(n-1)+fibo(n-2);}}
import java.util.Random;
public class QuickSort {
/**
* @param args
*/
static int arr[] = new int[10];
public static void main(String[] args) {
// TODO Auto-generated method stub
Random generator = new Random();
for(int i =0;i<10;i++){
arr[i] = generator.nextInt(20);
System.out.println(arr[i]);
}
sort(0,9);
System.out.println("Sorted Array");
for(int i =0;i<10;i++){
System.out.println(arr[i]);
}
}
public static void sort(int low , int high){
int i = low;int j =high;
int pivot = arr[low+(high-low)/2];
while(i<=j){
while(arr[i]<pivot){
i++;
}
while(arr[j]>pivot){
j--;
}
if(i<=j){
exchange(i,j);
i++;
j--;
}
}
if(low<j){
sort(low,j);
}
if(i<high){
sort(i,high);
}
}
private static void exchange(int i, int j) {
// TODO Auto-generated method stub
int temp = arr[i];
arr[i] =arr[j];
arr[j]=temp;
}
}
import java.util.Arrays;
public class BucketSort {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
int[] arr = {4,6,1,8,11,23};
int[] tmparr = new int[24] ;
System.out.println("Unsorted List");
for (int i=0;i<arr.length;i++){
System.out.println(arr[i]);
tmparr[arr[i]] =1;
}
System.out.println("Sorted List");
for (int i=0;i<tmparr.length;i++){
if(tmparr[i]==1){
System.out.println(i);
}
}
bucketSort(arr);
for (int i = 0; i < arr.length; i++) {
System.out.print(arr[i] + " ");
}
}
public static int[] bucketSort(int[] arr) {
int i, j;
int[] count = new int[arr.length];
Arrays.fill(count, 0);
for (i = 0; i < arr.length; i++) {
count[arr[i]]++;
}
for (i = 0, j = 0; i < count.length; i++) {
for (; count[i] > 0; (count[i])--) {
arr[j++] = i;
}
}
return arr;
}
}
public class ReverseNumber {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
int num = 78539;
int revNum = 0;
while(num!=0){
revNum = revNum*10 + num%10;
num = num/10;
}
System.out.println(revNum);
}
}
public class ReverseString {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
String s = "WORLD";
System.out.println(reverse(s));
}
public static String reverse(String str){
if(str.length()==1)
return str;
else
return reverse(str.substring(1)) + str.charAt(0);
}
}
public class Permutation {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
String str = "waffle";
permute("", str);
}
public static void permute (String prefix , String str)
{
int n = str.length();
if(n==0){
System.out.println(prefix);
}else{
for (int i =0 ;i<n;i++){
permute(prefix+str.charAt(i),str.substring(0,i)+str.substring(i+1,str.length()));
}
}
}
}
BinarySearch
public class BinarySearch
{
public static void main(String[]args)
{
System.out.println("d");
int[]data={1,1,2,3,1,1,1};
System.out.println(count(data,1));
}
public static int count(int[] a, int x)
{
int low=0;
int high = a.length-1;
int count=0;
while(low <=high)
{
int mid=((low+high)/2);
if(x>a[mid])
low=mid+1;
if(x<a[mid])
high=mid-1;
if(x==a[mid])
{
System.out.println(mid);
int top=findTopIndex(a,x,mid);
int bottom=findBottomIndex(a,x,mid);
return (top-bottom);
}
}
return 111111111;
}
public static int findTopIndex(int[] a, int x, int index)
{
int low=index;
int high = a.length-1;
int mid;
if(x==a[high])
return high;
while(low <= high)
{
mid=((low+high)/2);
if(x<a[mid]&&x==a[mid-1])
return mid-1;
else if(x==a[mid])
low=mid+1;
else if(a[mid]>x && a[mid-1]!=x)
high=mid-1;
}
return 11111111;
}
public static int findBottomIndex(int[] a, int x, int index)
{
int low=0;
int high = index-1;
int mid;
if(x==a[low])
return low-1;
while(low <= high)
{
mid=((low+high)/2);
if(x>a[mid]&&x==a[mid+1])
return mid;
else if(x==a[mid])
high=mid-1;
else if(a[mid]<x && a[mid+1]!=x)
low=mid+1;
}
return 111;
}
}
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