From 《编程珠玑》:一个文件中至多包含n个不重复的正整数,每个正整数都小于n,这里n=10^7。要求:以增量的形式输出经排序后的整数(限用1M内存)。
思路1:1M内存大约可以存储250000个整数。因此我们可以对输入文件遍历40次,第一次遍历过程中将值大于0、小于249999的所有整数读入内存,然后进行快速排序,再写入目标文件;第二次遍历过程中将值大于250000、小于499999的所有整数读入内存,排完序后写入目标文件,后面依此类推;第40次遍历过程中将大于9750000、小于9999999的所有整数读入内存,排完序后写入目标文件。此时目标文件中的整数已按增量排完序,顺序输出即可。
思路2:系统排序
(Command命令行)>sort originalFileName.ext >> targetFileName.ext
思路3:位图数据结构。
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如果不限内存,还可以使用下面两种排序方法:
思路1:C++/STL
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思路2:C/qsort
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