public void sortColors(int[] A) {
		if(A == null || A.length == 0) return;
		int leftOne = -1, cur = 0, right = A.length - 1;
		
		while(cur <= right) {
			if(A[cur] == 0) {
				if(leftOne != -1) {
					A[leftOne++] = 0;
					A[cur] = 1;
				}
				cur++;
			} else if(A[cur] == 1) {
				if(leftOne == -1) leftOne = cur;
				cur++;
			} else {
				A[cur] = A[right];
				A[right--] = 2;
			}
		}
	}