no. of permutations of an array code example
Example: how to get all permutations of an array
ArrayList<int []> heap(int [] input) {
ArrayList<int []> ret = new ArrayList<int []> ();
ret = generate(input.length, input, ret);
return ret;
}
ArrayList<int []> generate(int k, int [] a, ArrayList<int []> output) {
if (k == 1) {
output.add(a.clone());
} else {
output = generate(k-1, a, output);
for (int i=0; i<k-1; i++) {
if (k%2 == 0) {
int temp = a[i];
a[i] = a[k-1];
a[k-1] = temp;
} else {
int temp = a[0];
a[0] = a[k-1];
a[k-1] = temp;
}
generate(k-1, a, output);
}
}
return output;
}