图解排序算法

讨论

Sorting nearly sorted data is quite common in practice. Some observations:

• Insertion sort is the clear winner on this initial condition.
• Bubble sort is fast, but insertion sort has lower overhead.
• Shell sort is fast because it is based on insertion sort.
• Merge sort, heap sort, and quick sort do not adapt to nearly sorted data.

Insertion sort provides a O(n²) worst case algorithm that adapts to O(n) time when the data is nearly sorted. One would like an O(n·lg(n)) algorithm that adapts to this situation; smoothsort is such an algorithm, but is complex. Shell sort is the only sub-quadratic algorithm shown here that is also adaptive in this case.

指示

• 点击来重新启动在行、列或整个表格中的动画。
• 可以直接点击动画图像来启动或重新启动它。
• 点击问题的规模来重置所有的动画。

关键

• 黑色的值是已经排好序的。
• 灰色的值是还未完成排序的。
• 一个红色的三角形标记算法的位置。
• 深灰色的值表示当前时间间隔(希尔排序, 归并排序, 快速排序)。
• 一对红色的三角形标记着左、右指针(快速排序)。

参考文档

Algorithms in Java, Parts 1-4, 3rd edition by Robert Sedgewick. Addison Wesley, 2003.

Programming Pearls by Jon Bentley. Addison Wesley, 1986.

Quicksort is Optimal by Robert Sedgewick and Jon Bentley, Knuthfest, Stanford University, January, 2002.

Dual Pivot Quicksort: Code and Discussion.

Bubble-sort with Hungarian ("Csángó") folk dance YouTube video, created at Sapientia University, Tirgu Mures (Marosvásárhely), Romania.

Select-sort with Gypsy folk dance YouTube video, created at Sapientia University, Tirgu Mures (Marosvásárhely), Romania.

Sorting Out Sorting, Ronald M. Baecker with the assistance of David Sherman, 30 minute color sound film, Dynamic Graphics Project, University of Toronto, 1981. Excerpted and reprinted in SIGGRAPH Video Review 7, 1983. Distributed by Morgan Kaufmann, Publishers. Excerpt.