[Design] Big Data - Find Existence of a Number - Shuatiblog.com
给40亿个不重复的unsigned int的整数，没排过序的，然后再给一个数，如何快速判断这个数是否在那40亿个数当中？
Analysis
Categorized under BitMap.
There're 4.3 billion unsigned integers in Java. This is a perfect question to use BitMap.
申请512M的内存，一个bit位代表一个unsigned int值。读入40亿个数，设置相应的bit位，读入要查询的数，查看相应bit位是否为1，为1表示存在，为0表示不存在。
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