Permutation.java

package codingProblems;

//Java program to print all combination of size r in an array of size n
import java.io.*;

class Permutation {

 /* arr[]  ---> Input Array
 data[] ---> Temporary array to store current combination
 start & end ---> Staring and Ending indexes in arr[]
 index  ---> Current index in data[]
 r ---> Size of a combination to be printed */
 static void combinationUtil(int arr[], int n, int r, int index,
                             int data[], int i)
 {
     // Current combination is ready to be printed, print it
     if (index == r)
     {
         for (int j=0; j<r; j++)
             System.out.print(data[j]+" ");
         System.out.println("");
     return;
     }

     // When no more elements are there to put in data[]
     if (i >= n)
     return;

     // current is included, put next at next location
     data[index] = arr[i];
     combinationUtil(arr, n, r, index+1, data, i+1);

     // current is excluded, replace it with next (Note that
     // i+1 is passed, but index is not changed)
     combinationUtil(arr, n, r, index, data, i+1);
 }

 // The main function that prints all combinations of size r
 // in arr[] of size n. This function mainly uses combinationUtil()
 static void printCombination(int arr[], int n, int r)
 {
     // A temporary array to store all combination one by one
     int data[]=new int[r];

     // Print all combination using temprary array 'data[]'
     combinationUtil(arr, n, r, 0, data, 0);
 }

 /*Driver function to check for above function*/
 public static void main (String[] args) {
     int arr[] = {1, 2, 3, 4, 5};
     int r = 3;
     int n = arr.length;
     printCombination(arr, n, r);
 }
}