回頭看酷殼上那篇《一些有意思的算法代碼》，在清單上看到第一條是Binomial Heap，回想一下好像是算法導論里剛剛研習過的內容，對，是二項堆，特別想看看具體的實現，點開鏈接看到滿滿的注釋，頓時幸福洋溢。再看作者，Keith Schwarz，他是一個斯坦福大學計算機科學系的講師，在自己的網站放了一些自己實現的算法和數據結構，覺得挺好的，有空可以去看看，這是鏈接：http://www.keithschwarz.com/interesting/。
改天再談談二項堆的內容，今天先貼一個應該是其中最短的代碼，Random Shuffle隨機洗牌，隨便學習一下算法和C++。（這位老師還非常願意分享自己的代碼，只是注滿注釋的代碼顯得太長了）
代碼注釋很多也很淺顯，就不翻譯了。雖說核心的代碼就兩行，但是里面的所有內容還是很應該學習的，比如，可以在自選范圍內進行隨機排列，可以傳入自定義的隨機數產生算法，使用了模板這樣任何數據類型都可以進行排列。這個算法核心的意思也就一句話來概括：隨機選取一個數組元素，和第一個元素進行交換，然后繼續按照這種方法處理剩下的數組元素，只需要線性時間和常量空間即可。
這里面還有一點沒有想到的是，在函數參數列表里居然可以傳入函數名稱，然后在里面執行這個傳入的函數，難道是函數指針，C++真是忘得差不多了。
==================================================================================
/**************************************************************************
* File: RandomShuffle.hh
* Author: Keith Schwarz (htiek@cs.stanford.edu)
*
* An implemention of a function for randomly permuting the elements of a
* sorted range. The algorithm is an implementation of the Fisher-Yates
* shuffle (also called the Knuth shuffle), which works by randomly selecting
* an element from the the array and swapping it to the front, then recursively
* repeating the process on the rest of the array. It runs in linear time
* and with only constant space.
*
* This implementation, by default, works using the system rand function,
* which is not ideal if cryptographic randomness is desired. Consequently,
* like the STL algorithm random_shuffle, the algorithm allows for a custom
* random generator to be passed into the function.
*/
#ifndef RandomShuffle_Included
#define RandomShuffle_Included
#include <algorithm> // For iter_swap
#include <cstdlib> // For rand
/**
* Function: RandomShuffle(RandomIterator begin, RandomIterator end);
* ------------------------------------------------------------------------
* Randomly permutes the elements in the range [begin, end), using the system
* rand function as a source of randomness.
*/
template <typename RandomIterator>
void RandomShuffle(RandomIterator begin, RandomIterator end);
/**
* Function: RandomShuffle(RandomIterator begin, RandomIterator end,
* RandomGenerator rng);
* ------------------------------------------------------------------------
* Randomly permutes the elements in the range [begin, end), using the
* provided callback as a source of randomness. The generator should be
* callable as a nullary function which produces a uniformly-distributed
* random value over a range at least as large as the input range.
*/
template <typename RandomIterator, typename RandomGenerator>
void RandomShuffle(RandomIterator begin, RandomIterator end,
RandomGenerator rnd);
/* * * * * Implementation Below This Point * * * * */
/* Main implementation of the algorithm. */
template <typename RandomIterator, typename RandomGenerator>
void RandomShuffle(RandomIterator begin, RandomIterator end,
RandomGenerator rnd) {
/* Iterate across the elements, picking a random element and swapping it
* to the front at each step.
*/
for (RandomIterator itr = begin; itr != end; ++itr)
std::iter_swap(itr, itr + rnd() % (end - itr));
}
/* Default implementation just uses rand. */
template <typename RandomIterator>
void RandomShuffle(RandomIterator begin, RandomIterator end) {
RandomShuffle(begin, end, std::rand);
}
#endif
==================================================================================