我們觀察規律發現,我們每一位會跟後面的位置進行互換,這樣的我們就遞迴就好.

public class demo {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		int a[] = {1,2,3,4};
		int left = 0;
		int right = a.length - 1;
		solve(a,left,right);
	}

	private static void solve(int[] a, int left, int right) {
		// TODO Auto-generated method stub
		if(left==right){
			for(int i = 0;i<a.length;i++){
				System.out.print(a[i]);
			}
			System.out.println();
		}else{
			for(int i = left;i<=right;i++){
				swap(a,left,i);
				solve(a,left+1,right);
				swap(a,left,i);
			}
		}
	}

	private static void swap(int[] a, int left, int right) {
		int temp = a[left];
		a[left] = a[right];
		a[right] = temp;
	}

}