只是一个简单的算法来小整数排序，但它必须是O（N）。
Just a simple algorithm to sort small integers, but it must be O(n).
推荐答案一个基数排序是一种方法这是 O（N）。既然你要处理的小整数，应该不会太难实现。
A radix sort is one approach that's O(n). Since you're dealing with small integers, it shouldn't be too hard to implement.