Java Utililty Methods Array Permute

int[] permutation(final int start, final int end)
Creates a permutation of all integers in the interval [start, end]

if (start > end)
 return new int[0];
final int length = end - start + 1;
final int[] r = new int[length];
for (int i = 0; i < length; i++)
 r[i] = start + i;
for (int i = length - 1; i > 0; i--) {
 final int j = random.nextInt(i + 1);
...

int[] permutation(int n)
Generates a random permutation of the numbers {0, ..., n-1}

return permutation(n, getRandomGenerator());

Object[] permute(int k, Object[] os)
permute

for (int j = 2; j <= os.length; j++) {
 k = k / (j - 1);
 Object tmp = os[j - 1];
 os[j - 1] = os[(k % j)];
 os[(k % j)] = tmp;
return os;

void permute(int[] elements, int i, int j)
permute

int temp;
temp = elements[i];
elements[i] = elements[j];
elements[j] = temp;

int[] permute(int[] in, int[] idx)
permute

int[] out = new int[in.length];
for (int i = 0; i < in.length; i++)
 out[i] = in[idx[i]];
return out;

Object[] permute(int[] p, Object[] data, boolean clone)
Rearrange the specified data according to the specified permutation.

Object[] permuted = null;
if (clone) {
 permuted = (Object[]) data.clone();
 for (int i = 0; i < data.length; i++)
 permuted[p[i]] = data[i];
} else {
 int i = 0;
 while (i < p.length) {
...

void permute(String str, int startIndex, int endIndex)
Algo {A,B,C} first take index 0 and swap with all A swap with A {A,B,C} ---> now take second char and make first char fixed {A,B,C} and {A,C,B} A swap with B {B,A,C} ---> now take second char and make first char fixed {B,A,C} and {B,C,A} A swap with C {C,B,A} ---> now take second char and make first char fixed {C,B,A} and {C,A,B} now take second char on each

if (startIndex == endIndex) {
 System.out.println(str);
} else {
 for (int i = startIndex; i <= endIndex; i++) {
 str = swap(str, startIndex, i);
 permute(str, startIndex + 1, endIndex);
 str = swap(str, startIndex, i);

void permute(T[] array)
Randomly permute the values in array .

Collections.shuffle(Arrays.asList(array));

T[] permute(T[] values)
"Randomly" permute an array in place.

for (int i = 0; i < values.length; i++) {
 swap(values, i, generator.nextInt(values.length));
return values;

int[] permuteArray(int[] array, Integer[] permutation)
permute Array

int[] output = new int[array.length];
for (int i = 0; i < output.length; i++) {
 output[i] = array[permutation[i]];
return output;