C++ 标准模板库中的排序

partial_sort()函数

partial_sort接受一个middle迭代器，使序列中的middle-first个最小元素以递增顺序排序，置于[first, middle)内。

template <class RandomAccessIterator>  void partial_sort (RandomAccessIterator first, RandomAccessIterator middle, RandomAccessIterator last);

//包含比较函数的声明template <class RandomAccessIterator, class Compare>  void partial_sort (RandomAccessIterator first, RandomAccessIterator middle, RandomAccessIterator last, Compare comp);

示例代码：

int a[] = {1,4,3,6,7,2,5};vector<int> v1(a, a + 7);partial_sort(v1.begin(), v1.begin() + 3, v1.end());

partial_sort_copy()函数

参数意思和partial_sort()函数一样，多出来的是将排序的这部分存入到以result_first为首指针的数组中去（不超过result_last 尾指针），如果原来存储了内容，就覆盖。

template <class InputIterator, class RandomAccessIterator>   RandomAccessIterator     partial_sort_copy ( InputIterator first,InputIterator last,                         RandomAccessIterator result_first,                         RandomAccessIterator result_last ); //返回值：指向结果序列中写入的最后一个元素之后的元素的迭代器。

//包含比较函数的声明template <class InputIterator, class RandomAccessIterator, class Compare>   RandomAccessIterator     partial_sort_copy ( InputIterator first,InputIterator last,                         RandomAccessIterator result_first,                         RandomAccessIterator result_last,                         Compare comp ); //返回值：指向结果序列中写入的最后一个元素之后的元素的迭代器。

示例代码：

int a[] = {1,4,3,6,7,2,5};vector<int> v1(a, a + 7), v2;vector<int>::iterator i1;i1 = partial_sort_copy(v1.begin(), v1.begin() + 4, v2.begin(), v2.end());

sort

对给定区间所有元素进行排序

template <class RandomAccessIterator>  void sort (RandomAccessIterator first, RandomAccessIterator last);

//包含比较函数的声明template <class RandomAccessIterator, class Compare>  void sort (RandomAccessIterator first, RandomAccessIterator last, Compare comp);

示例代码：

int a[] = {1,4,3,6,7,2,5};vector<int> v1(a, a + 7);sort(v1.begin(), v1.begin() + 3, v1.end());

stable_sort

stable_sort()可以对vector的成员进行排序，可保证相等元素的原本相对次序在排序后保持不变

template <class RandomAccessIterator>  void stable_sort ( RandomAccessIterator first, RandomAccessIterator last );

//包含比较函数的声明template <class RandomAccessIterator, class Compare>  void stable_sort ( RandomAccessIterator first, RandomAccessIterator last, Compare comp );

示例代码：

int a[] = {1,4,3,6,7,2,5};vector<int> v1(a, a + 7);stable_sort(v1.begin(), v1.begin() + 3, v1.end());

sort_heap：

将一个堆做排序,最终成为一个有序的系列，可以看到sort_heap时，必须先是一个堆（两个特性：1、最大元素在第一个 2、添加或者删除元素以对数时间），因此必须先做一次make_heap.
几个相关的函数：

• make_heap：将[start, end)范围进行堆排序，默认使用less< int >, 即最大元素放在第一个
• push_heap：将front（即第一个最大元素）移动到end的前部，同时将剩下的元素重新构造成(堆排序)一个新的heap
• pop_heap：对刚插入的（尾部）元素做堆排序

template <class RandomAccessIterator>  void sort_heap (RandomAccessIterator first, RandomAccessIterator last);

示例代码：

int a[] = {1,4,3,6,7,2,5};vector<int> v1(a, a + 7);make_heap(v1.begin(), v1.end());sort_heap(v1.begin(), v1.end());

//包含比较函数的声明template <class RandomAccessIterator, class Compare>  void sort_heap (RandomAccessIterator first, RandomAccessIterator last, Compare comp);

完整代码如下：

#include <iostream>#include <vector>#include <algorithm>#include <functional>   //greater()using namespace std;class Person{public:    Person(char *ch = "", int n = 0){        name = strdup(ch);        age = n;    }    bool operator==(const Person &p) const {        return strcmp(name, p.name) == 0;    }    bool operator<(const Person &p) const {        return strcmp(name, p.name) < 0;    }private:    char *name;    int age;    friend ostream &operator<<(ostream &out, const Person &p){        out << "(" << p.name << "," << p.age << ")";        return out;    }};bool f1(int n){    return n < 5;}template<class T>void printVector(char *s, const vector<T> &v){    cout << s << " = (";    if(v.size() == 0){        cout << ")\n";        return ;    }    vector<T>::const_iterator i;    for(i = v.begin(); i != v.end() - 1; i++)        cout << *i << ',';    cout << *i << ")\n";}int main(){    int a[] = {1,4,3,6,7,2,5};    vector<int> v1(a, a + 7), v2(a, a + 7), v3(6, 9), v4(6, 9);    vector<int>::iterator i1, i2, i3, i4;    partial_sort(v1.begin(), v1.begin() + 3, v1.end());    printVector("v1", v1);    partial_sort(v2.begin() + 1, v2.begin() + 4, v2.end(), greater<int>());    printVector("v2", v2);    i3 = partial_sort_copy(v2.begin(), v2.begin() + 4, v3.begin(), v3.end());    printVector("v3", v3);    cout << *(i3 - 1) << ' ' << *i3 << endl;    i4 = partial_sort_copy(v1.begin(), v1.begin() + 4, v4.begin(), v4.end(), greater<int>());    printVector("v4", v4);    cout << *(i4 - 1) << ' ' << *i4 << endl;    i1 = partition(v1.begin(), v1.end(), f1);    printVector("v1", v1);    cout << *(i1 - 1) << ' ' << *i1 << endl;    i2 = partition(v2.begin(), v2.end(), bind2nd(less<int>(), 5));    printVector("v2", v2);    cout << *(i2 - 1) << ' ' << *i2 << endl;    sort(v1.begin(), v1.end());    sort(v1.begin(), v1.end(), greater<int>());    vector<Person> pv1, pv2;    for(int i = 0; i < 20; i++){        pv1.push_back(Person("Josie", 60 - i));        pv2.push_back(Person("Josie", 60 - i));    }    sort(pv1.begin(), pv1.end());    stable_sort(pv2.begin(), pv2.end());    vector<int> heap1, heap2, heap3(a, a + 7), heap4(a, a + 7);    for(int i = 0; i < 7; i++){        heap1.push_back(i);        push_heap(heap1.begin(), heap1.end());        printVector("heap1", heap1);    }    sort_heap(heap1.begin(), heap1.end());    for(int i = 0; i < 7; i++){        heap2.push_back(i);        push_heap(heap2.begin(), heap2.end(), greater<int>());        printVector("heap2", heap2);    }    sort_heap(heap2.begin(), heap2.end(), greater<int>());    printVector("heap2", heap2);    make_heap(heap3.begin(),heap3.end());    sort_heap(heap3.begin(), heap3.end());    make_heap(heap4.begin(),heap4.end(), greater<int>());    printVector("heap4", heap4);    sort_heap(heap4.begin(),heap4.end(), greater<int>());    printVector("heap4", heap4);    return 0;}

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PS：比较函数
greater<T>()

//重载括号为比较大小template <class T> struct greater : binary_function <T,T,bool> {  bool operator() (const T& x, const T& y) const {return x>y;}};

less<T>()

//重载括号为比较大小template <class T> struct less : binary_function <T,T,bool> {  bool operator() (const T& x, const T& y) const {return x<y;}};