public static int[] bubble(int[] array) {
		if(array==null || array.length==0) return array;
		int tmp;
		int cnt=0;
		for(int i=0;i<array.length;++i) {
			for(int j=0;j<array.length-i-1;++j) {
				if(array[j]>array[j+1]) {
					cnt++;
					tmp = array[j];
					array[j] = array[j+1];
					array[j+1] = tmp;
				}
			}
		}
		System.out.print("Bubble sort, N="+array.length+", Excution times="+cnt+", Extra Space=0");
		return array;
	}