排序算法@c++描述-插入排序

1.插入排序

普通版本

#include <iostream>#include <vector>#include <ctime>using namespace std;template <typename T>void insertionSort(vector<T> &a){    int i;    for (int j = 1; j < a.size(); j++) {        T tmp = a[j];        for (i = j; i > 0 && tmp < a [i - 1]; i--)            a[i] = a[i - 1];        a[i] = tmp;    }}int main(){    vector<int> test = {190, 435, 834, 8954, 923, 56, 20 ,1, 934};    clock_t time_stt = clock();    insertionSort(test);    cout << "Total time: " << 1000 * (clock() - time_stt) / (double)CLOCKS_PER_SEC << "ms" << endl;    for (auto i : test)        cout << i << " ";    cout << endl;    return 0;}

• 运行结果：

$ ./a.outTotal time: 0.002ms1 20 56 190 435 834 923 934 8954

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STL实现版本(模仿STL sort() 接口)

#include <iostream>#include <vector>#include <ctime>using namespace std;// 模仿STL sort()接口template <typename Iterator, typename Object, typename Functor>void insertionSort(const Iterator &begin, const Iterator &end, Functor func, const Object &obj){    Iterator i;    for (Iterator j = begin + 1; j != end; j++) {        Object tmp = *j;        for (i = j; i != begin && func(tmp, *(i - 1)); i--)            *i = *(i - 1);        *i = tmp;    }}template <typename Iterator, typename Functor>void insertionSort(const Iterator &begin, const Iterator &end, Functor func){    insertionSort(begin, end, func, *begin);}template <typename Iterator, typename Object>void _insertionSort(const Iterator &begin, const Iterator &end, const Object &obj){    insertionSort(begin, end, less<Object>());}template <typename Iterator>void insertionSort(const Iterator &begin, const Iterator &end){    _insertionSort(begin, end, *begin);}int main(){    vector<int> test = {190, 435, 834, 8954, 923, 56, 20 ,1, 934};    clock_t time_stt = clock();    insertionSort(test.begin(), test.end());    cout << "Total time: " << 1000 * (clock() - time_stt) / (double)CLOCKS_PER_SEC << "ms" << endl;    for (auto i : test)        cout << i << " ";    cout << endl;    return 0;}

• 运行结果：

$ ./a.outTotal time: 0.005ms1 20 56 190 435 834 923 934 8954 

仿函数

此时引入了仿函数(也叫函数结构，functor)，可以对排序顺序进行自定义

比如可以利用lambda讲排序结果反过来：

#include <iostream>#include <vector>#include <ctime>using namespace std;// 模仿STL sort()接口template <typename Iterator, typename Object, typename Functor>void insertionSort(const Iterator &begin, const Iterator &end, Functor func, const Object &obj){    Iterator i;    for (Iterator j = begin + 1; j != end; j++) {        Object tmp = *j;        for (i = j; i != begin && func(tmp, *(i - 1)); i--)            *i = *(i - 1);        *i = tmp;    }}template <typename Iterator, typename Functor>void insertionSort(const Iterator &begin, const Iterator &end, Functor func){    insertionSort(begin, end, func, *begin);}template <typename Iterator, typename Object>void _insertionSort(const Iterator &begin, const Iterator &end, const Object &obj){    insertionSort(begin, end, less<Object>());}template <typename Iterator>void insertionSort(const Iterator &begin, const Iterator &end){    _insertionSort(begin, end, *begin);}int main(){    vector<int> test = {190, 435, 834, 8954, 923, 56, 20 ,1, 934};    clock_t time_stt = clock();    insertionSort(test.begin(), test.end(), [](int a, int b){        if (a > b)            return 1;        else            return 0;    });    cout << "Total time: " << 1000 * (clock() - time_stt) / (double)CLOCKS_PER_SEC << "ms" << endl;    for (auto i : test)        cout << i << " ";    cout << endl;    return 0;}

• 运行结果：

$ ./a.outTotal time: 0.006ms8954 934 923 834 435 190 56 20 1 

复杂度分析

最坏情况

T(N)=1+2+3+...+(N−1)

时间复杂度：

O(n2)

最好情况

T(N)=N−1

时间复杂度：

O(n)

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