全排列

//全排列,给一个数组，输出数组中所有元素的全排列
public class Permutation {
	public void permutation(int a[], int low, int high) {
		if (low >= high) {
			for (int i = 0; i < a.length; i++) {
				System.out.print(a[i]);
			}
			System.out.println();
			return;
		}
		for (int k = low; k <= high; k++) {
			swap(a, low, k);
			permutation(a, low + 1, high);
			swap(a, low, k);
		}
	}

	public void swap(int a[], int pos1, int pos2) {
		int temp = a[pos1];
		a[pos1] = a[pos2];
		a[pos2] = temp;
	}

	public static void main(String[] args) {
		Permutation pta = new Permutation();
		int[] a = { 1, 2, 3,4};
		 pta.permutation(a, 0, a.length - 1);
	}
}