public static List<int[]> collect = new ArrayList<int[]>();

	public static void permutation(int[] a, int begin0, int begin, int mid1, int mid2, int end, int selectNum) {

		int[] temp = new int[selectNum];
		System.arraycopy(a, begin0, temp, 0, selectNum);
		collect.add(temp);

		for (int t = begin; t < mid1; t++) {
			for (int j = mid2; j < end; j++) {
				int temp0 = a[t];
				a[t] = a[j];
				a[j] = temp0;
						
				permutation(a, begin0, t + 1, mid1, j + 1, end, selectNum);
				
				a[j] = a[t];
				a[t] = temp0;
			}
		}

	}

	public static void main(String[] args) {
		int[] a = { 1, 2, 3, 4, 5};
		
		int begin = 0; //從哪裡開始選
		int selectNum = 3; //選擇幾個
		
		int mid = begin + selectNum;
		if(mid <= a.length)
			permutation(a, begin, begin, mid, mid, a.length, selectNum);

		int[][] b = new int[collect.size()][]; // 列印驗證
		collect.toArray(b);
		for (int i = 0; i < b.length; i++) {
			int[] nums = b[i];
			for (int j = 0; j < nums.length; j++) {
				System.out.print(nums[j]);
			}
			System.out.println();
		}
	}