August 2017
Intermediate to advanced
360 pages
8h 35m
Chinese
Content preview from 算法技术手册（原书第2 版）
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18
｜
第
2
章
问题规模（如规模小于
7
、在
8
和
39
之间以及达到
40
或者甚至更大），采用不同的策
略对快速排序进行优化。实验结果表明，这个隐藏的优化手段非常有效。
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o
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µsDž
ຕࡀఇ
o
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图 2-1：小数据集上四种排序算法的比较结果
2.3 最好、最坏和平均情况下的性能分析
也许有人会问，上述结果是否对于所有的输入问题样本都成立？
第二种排序算法
对于同
等规模的其他数据样本表现会如何呢？
•
输入数据可能包含大量已排好序的元素。
•
输入数据可能包含重复值。
算法的数学原理
｜
19
算法的
数学原理
•
无论输入数据规模
n
是多少，元素集合都可以从一个非常小的数据集扩展而来，只
不过会有相当多的重复值。
从图
2-1
上可以看出，
第四种排序算法
虽然在排序
n
个乱序字符串时最慢，但它在处理
已经排好序的数据时却是最快的。不过，这种领先优势消失得非常快，如图
2-2
所示，
在排序
32
个乱序的字符串时，
第三种排序算法
的性能最好。
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o
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ኴႜ้क़DŽڇ࿋ǖµsDž
ຕࡀఇ
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ಇႾ໙݆2 ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.