//所有容器适用

nth_element(b,n,e)
nth_element(b,n,e,p)
对比：partition()算法

/**------http://blog.csdn.net/u010579068------**/  #include<iostream>  #include<cstdio>  #include<string>  #include<vector>  #include<list>  #include<functional>  #include<deque>  #include<algorithm>  using namespace std;    /*****************************************  //所有容器适用  nth_element(b,n,e)  nth_element(b,n,e,p)  对比：partition()算法  *****************************************/  /**----------------------------------------------------------------------------------    ----------------------------------------------------------------------------------**/  /*************************************************************************************  std::nth_element                    所有排序容器适用                        algorithm  --------------------------------------------------------------------------------------  template <class RandomAccessIterator>    void nth_element ( RandomAccessIterator first, RandomAccessIterator nth,                       RandomAccessIterator last );    template <class RandomAccessIterator, class Compare>    void nth_element ( RandomAccessIterator first, RandomAccessIterator nth,                       RandomAccessIterator last, Compare comp );  //eg：    *************************************************************************************/      bool myfunction (int i,int j)  {      return (i>j);  }    int main ()  {      int m[]= {3,4,5,6,7,2,3,4,5,6,1,2,3,4,5};      vector<int> myvector(m,m+15);      vector<int>::iterator it;    //  set some values:  //    for (int i=1; i<10; i++) myvector.push_back(i);   // 1 2 3 4 5 6 7 8 9    //    random_shuffle (myvector.begin(), myvector.end());        cout << "myvector contains:(原始数据)";      for (it=myvector.begin(); it!=myvector.end(); ++it)          cout << " " << *it;        cout << endl;  //   using default comparison (operator <):  //   cout<<*(myvector.begin()+3)<<endl;      nth_element (myvector.begin(), myvector.begin()+3, myvector.end());        cout << "myvector contains:(从小到大)";      for (it=myvector.begin(); it!=myvector.end(); ++it)          cout << " " << *it;        cout << endl;    //  using function as comp  //    cout<<*(myvector.end()-4)<<endl;  //    nth_element (myvector.begin(), myvector.begin()+3, myvector.end(),myfunction);      nth_element (myvector.begin(), myvector.end()-4, myvector.end(),greater<int>());      // print out content:      cout << "myvector contains:(从大到小)";      for (it=myvector.begin(); it!=myvector.end(); ++it)          cout << " " << *it;        cout << endl;        return 0;  }