老老实实复习算法: 1 插入排序

干了15年程序员了, 乐在其中, 还能继续干下去. 这几天开始复习一下算法, 于是购得一本<算法导论>, 慢慢啃之. 

 

<算法导论>中的数组下标都是从1开始的, 但我实现的 c++ 代码中, 都是 0 开始.

 

插入排序

INSERTION_SORT(A)

for j = [2, len(A)]

key = A[j]

i = j - 1

while i > 0 and A[i] > key

A[i+1] = A[i]

i--

A[i+1] = key

 

C++实现代码如下:

#ifndef _sort_insertion__hh#define _sort_insertion__hh/** 插入排序, O(n^2), 属于"原地操作" // 排序 A 数组, 从 start 开始, size 个元素 INSERTION-SORT(A, start, size) for j = start+1 to start+size key = A[j] i = j-1; while i >= 0 and key < A[i] A[i+1] = A[i] i--; A[i+1] = key;*/template<class T>inline void algo_sort_insertion(T *array, size_t start, size_t size){ for (size_t j = start+1; j < (start+size); j++) { T key = array[j]; size_t i = j-1; while ((int)i >= start && key < array[i]) { array[i+1] = array[i]; i--; } array[i+1] = key; }}#endif // insertion.h

 

与之对应的测试程序如下: (这个测试程序将用于测试所有实现的排序算法)

#include <stdio.h>#include <stdlib.h>#include "insertion.h"#include "merge.h"#include "bubble.h"#include "heap.h"#include "quick.h"static int _data0[] = { 1, 3, 2, 6, 3, 5, 4, 1, 10, 100, -3, 1000};static int _data1[] = { 1, 3, 2, 6, 3, 5, 4, 1, 10, 100, -3, 1000};static int _data2[] = { -3, 1, 1, 2, 3, 3, 4, 5, 6, 10, 100, 1000};typedef void (*PFN_test)(int *array, size_t start, size_t size);PFN_test _test_func = 0;int main (){ size_t start = 1; fprintf(stdout, "testing sort ..../n"); // 这里测试实际的排序算法实现 _test_func = algo_sort_merge<int>; _test_func = algo_sort_insertion<int>; _test_func = algo_sort_bubble<int>; _test_func = algo_sort_heap<int>; _test_func = algo_sort_quick<int>; _test_func(_data1, start, sizeof(_data1)/sizeof(int)-start); for (int i = 0; i < sizeof(_data1)/sizeof(int); i++) { if (_data2[i] != _data1[i]) { fprintf(stdout, "%d[%d] ", _data1[i], _data2[i]); } else { fprintf(stdout, "%d ", _data1[i]); } } return 0;}