STL之排序算法

1.merge()
以下是排序和通用算法：提供元素排序策略
merge: 合并两个有序序列，存放到另一个序列。
例如：
vecIntA,vecIntB,vecIntC是用vector声明的容器，vecIntA已包含1,3,5,7,9元素，vecIntB已包含2,4,6,8元素

vecIntC.resize(9);  //扩大容量
merge(vecIntA.begin(),vecIntA.end(),vecIntB.begin(),vecIntB.end(),vecIntC.begin());

此时vecIntC就存放了按顺序的1,2,3,4,5,6,7,8,9九个元素
2.sort()
sort: 以默认升序的方式重新排列指定范围内的元素。若要改排序规则，可以输入比较函数。

//学生类
Class CStudent:
{
public:
    CStudent(int iID, string strName)
    {
        m_iID=iID;  
        m_strName=strName; 
    }
public:            
    int m_iID;
    string m_strName;
}

//学号比较函数
bool Compare(const CStudent &stuA,const CStudent &stuB)
{
         return (stuA.m_iID<strB.m_iID);
}
void main()
{
vector<CStudent> vecStu;
vecStu.push_back(CStudent(2,"老二"));
vecStu.push_back(CStudent(1,"老大"));
vecStu.push_back(CStudent(3,"老三"));
vecStu.push_back(CStudent(4,"老四"));
sort(vecStu.begin(),vecStu.end(),Compare);

//此时，vecStu容器包含了按顺序的"老大对象","老二对象","老三对象","老四对象"
}

3.random_shuffle()
random_shuffle: 对指定范围内的元素随机调整次序。
srand(time(0)); //设置随机种子

vector<int> vecInt;
vecInt.push_back(1);
vecInt.push_back(3);
vecInt.push_back(5);
vecInt.push_back(7);
vecInt.push_back(9);

string str("itcastitcast ");

random_shuffle(vecInt.begin(), vecInt.end());   //随机排序，结果比如：9,7,1,5,3
random_shuffle(str.begin(), str.end());        //随机排序，结果比如：" itstcasticat "

reverse()

vector<int> vecInt;
vecInt.push_back(1);
vecInt.push_back(3);
vecInt.push_back(5);
vecInt.push_back(7);
vecInt.push_back(9);

reverse(vecInt.begin(), vecInt.end());      //{9,7,5,3,1}

综合代码

void main_merge()
{
    vector<int> v1;
    v1.push_back(1);
    v1.push_back(3);
    v1.push_back(5);

    vector<int> v2;
    v2.push_back(2);
    v2.push_back(4);
    v2.push_back(6);

    vector<int> v3;
    v3.resize(v1.size() + v2.size() );

    merge(v1.begin(), v1.end(), v2.begin(), v2.end(), v3.begin() );

    printV(v3);
}

class Student
{
public:
    Student(string name, int id)
    {
        m_name = name;
        m_id = id;
    }
    void printT()
    {
        cout << "name: " << m_name << " id " << m_id << endl;
    }
public:
    string  m_name;
    int     m_id;
};

bool CompareS(Student &s1, Student &s2)
{
    return (s1.m_id < s2.m_id);
}


void main_sort()
{
    Student s1("老大", 1);
    Student s2("老二", 2);
    Student s3("老三", 3);
    Student s4("老四", 4);
    vector<Student> v1;
    v1.push_back(s4);
    v1.push_back(s1);
    v1.push_back(s3);
    v1.push_back(s2);

    for (vector<Student>::iterator it=v1.begin(); it!=v1.end(); it++)
    {
        it->printT() ;
    }

    //sort 根据自定义函数对象 进行自定义数据类型的排序 
    //替换 算法的统一性 (实现的算法和数据类型的分离) ===>技术手段函数对象
    sort(v1.begin(), v1.end(), CompareS );

    for (vector<Student>::iterator it=v1.begin(); it!=v1.end(); it++)
    {
        it->printT() ;
    }

}

void main_random_shuffle()
{
    vector<int> v1;
    v1.push_back(1);
    v1.push_back(3);
    v1.push_back(5);
    v1.push_back(7);

    random_shuffle(v1.begin(), v1.end());
    printV(v1);

    string str = "abcdefg";
    random_shuffle(str.begin(), str.end());
    cout << "str: " << str << endl;
}

void main_reverse()
{
    vector<int> v1;
    v1.push_back(1);
    v1.push_back(3);
    v1.push_back(5);
    v1.push_back(7);
    reverse(v1.begin(), v1.end());
    printV(v1);
}