结果，返回的数组的长度不再与原始数组的长度一致。
As a result, the length of the returned array is no longer the same as the length of the original array.
检查数组如何分配，是一致的如何首页增加？
Check how array is allocated, is coherent with how index increases?
数组中选出数字的相对顺序应当与原数组保持一致。
The relative order of the digits from the same array must be preserved.
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