• 详细解说 STL 排序(Sort)
  • 0 前言: STL，为什么你必须掌握
  • 1 STL提供的Sort class="tags" href="/tags/SuanFa.html" title=算法>算法
    • 1.1 所有sortclass="tags" href="/tags/SuanFa.html" title=算法>算法介绍
    • 1.2 sort 中的比较函数
    • 1.3 sort 的稳定性
    • 1.4 全排序
    • 1.5 局部排序
    • 1.6 nth_element 指定元素排序
    • 1.7 partition 和stable_partition
  • 2 Sort 和容器
  • 3 选择合适的排序函数
  • 4 小结
  • 5 参考文档

vector < int > vect;
//...
sort(vect.begin(), vect.end());
//此时相当于调用
sort(vect.begin(), vect.end(), less<int>() );

#include <iostream>
#include <algorithm>
#include <functional>
#include <vector>
using namespace std;

class myclass {
        public:
        myclass(int a, int b):first(a), second(b){}
        int first;
        int second;
        bool operator < (const myclass &m)const {
                return first < m.first;
        }
};

bool less_second(const myclass & m1, const myclass & m2) {
        return m1.second < m2.second;
}

int main() {
        
        vector< myclass > vect;
        for(int i = 0 ; i < 10 ; i ++){
                myclass my(10-i, i*3);
                vect.push_back(my);
        }
        for(int i = 0 ; i < vect.size(); i ++) 
        cout<<"("<<vect[i].first<<","<<vect[i].second<<")/n";
        sort(vect.begin(), vect.end());
        cout<<"after sorted by first:"<<endl;
        for(int i = 0 ; i < vect.size(); i ++) 
        cout<<"("<<vect[i].first<<","<<vect[i].second<<")/n";
        cout<<"after sorted by second:"<<endl;
        sort(vect.begin(), vect.end(), less_second);
        for(int i = 0 ; i < vect.size(); i ++) 
        cout<<"("<<vect[i].first<<","<<vect[i].second<<")/n";
        
        return 0 ;
}

bool less_len(const string &str1, const string &str2)
{
        return str1.length() < str2.length();
}

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

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

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

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

#include <iostream>
#include <algorithm>
#include <functional>
#include <vector>
#include <string>
using namespace std;

class student{
        public:
        student(const string &a, int b):name(a), score(b){}
        string name;
        int score;
        bool operator < (const student &m)const {
                return score< m.score;
        }
};

int main() {
        vector< student> vect;
        student st1("Tom", 74);
        vect.push_back(st1);
        st1.name="Jimy";
        st1.score=56;
        vect.push_back(st1);
        st1.name="Mary";
        st1.score=92;
        vect.push_back(st1);
        st1.name="Jessy";
        st1.score=85;
        vect.push_back(st1);
        st1.name="Jone";
        st1.score=56;
        vect.push_back(st1);
        st1.name="Bush";
        st1.score=52;
        vect.push_back(st1);
        st1.name="Winter";
        st1.score=77;
        vect.push_back(st1);
        st1.name="Andyer";
        st1.score=63;
        vect.push_back(st1);
        st1.name="Lily";
        st1.score=76;
        vect.push_back(st1);
        st1.name="Maryia";
        st1.score=89;
        vect.push_back(st1);
        cout<<"------before sort..."<<endl;
        for(int i = 0 ; i < vect.size(); i ++) cout<<vect[i].name<<":/t"<<vect[i].score<<endl;
        stable_sort(vect.begin(), vect.end(),less<student>());
        cout <<"-----after sort ...."<<endl;
        for(int i = 0 ; i < vect.size(); i ++) cout<<vect[i].name<<":/t"<<vect[i].score<<endl;
        return 0 ;
}

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

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

template <class InputIterator, class RandomAccessIterator>
RandomAccessIterator partial_sort_copy(InputIterator first, InputIterator last,
RandomAccessIterator result_first,
RandomAccessIterator result_last);

template <class InputIterator, class RandomAccessIterator, 
class StrictWeakOrdering>
RandomAccessIterator partial_sort_copy(InputIterator first, InputIterator last,
RandomAccessIterator result_first,
RandomAccessIterator result_last, Compare comp);

stable_sort(vect.begin(), vect.end(),less<student>());
替换为：
partial_sort(vect.begin(), vect.begin()+5, vect.end(),less<student>());

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

template <class RandomAccessIterator, class StrictWeakOrdering>
void nth_element(RandomAccessIterator first, RandomAccessIterator nth,
RandomAccessIterator last, StrictWeakOrdering comp);

stable_sort(vect.begin(), vect.end(),less<student>());
替换为：
nth_element(vect.begin(), vect.begin()+3, vect.end(),less<student>());

template <class ForwardIterator, class Predicate>
ForwardIterator partition(ForwardIterator first,
ForwardIterator last, Predicate pred)
template <class ForwardIterator, class Predicate>
ForwardIterator stable_partition(ForwardIterator first, ForwardIterator last, 
Predicate pred);

stable_sort(vect.begin(), vect.end(),less<student>());
替换为：
student exam("pass", 60);
stable_partition(vect.begin(), vect.end(), bind2nd(less<student>(), exam));