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STL之排序演算法

1.merge()
以下是排序和通用演算法:提供元素排序策略
merge: 合併兩個有序序列,存放到另一個序列。
例如:
vecIntA,vecIntB,vecIntC是用vector宣告的容器,vecIntA已包含1,3,5,7,9元素,vecIntB已包含2,4,6,8元素

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

此時vecIntC就存放了按順序的1,2,3,4,5,6,7,8,9九個元素
2.sort()


sort: 以預設升序的方式重新排列指定範圍內的元素。若要改排序規則,可以輸入比較函式。

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

//學號比較函式
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); //此時,vecStu容器包含了按順序的"老大物件","老二物件","老三物件","老四物件"
}

3.random_shuffle()
random_shuffle: 對指定範圍內的元素隨機調整次序。
srand(time(0)); //設定隨機種子

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());   //隨機排序,結果比如:9,7,1,5,3
random_shuffle(str.begin(), str.end());        //隨機排序,結果比如:" 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}

綜合程式碼

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 根據自定義函式物件 進行自定義資料型別的排序 
    //替換 演算法的統一性 (實現的演算法和資料型別的分離) ===>技術手段函式物件
    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);
}