【c++算法】非变动性算法

非变动性算法: 既不改变元素次序，也不改变元素值

 

For_each()	对每个元素执行操作（也可做变动型算法）
Count	返回元素个数
Count_if	返回满足条件的元素个数
Min_element	返回最小元素，以一个迭代器表示
Max_element	返回最大元素，以一个迭代器表示
Find	搜索等于某一个值得第一个元素
Find_if	搜索满足条件的第一元素
Search	搜索某一区间第一次出现的位置
Search_n	搜索具有某特性的第一段n个连续元素
Find_end	搜索某个区间最后一次出现的元素
Find_first_of	搜索等于某个值得第一元素
Adjacent_find	搜索特定规则的元素
Equal	判断两个区间是否相等
Mismatch	返回两个序列的各组对应元素中，第一对不相等元素组
Lexicographical_compare	判断某一序列字典顺序下是否小于另一序列

 

--

#include <iostream>
#include <vector>
#include <vector>
#include <algorithm>
#include <iterator>

using namespace std;

template<class T>
class FunctionObjectType
{
private:
    T theValue;
public:
    FunctionObjectType(const T& v):theValue(v)
    {

    }
public:
    void operator()(T &i)
    {
        i += theValue;
    }
};

/*--------------打印元素-------------*/
template<class T>
inline void PrintElements(const T& coll,const char* optcstr="")
{
    typename T::const_iterator pos;

    std::cout<<optcstr;
    for(pos=coll.begin();pos != coll.end(); ++pos)
        std::cout<<*pos<<" ";

    std::cout<<endl;
}

template<class T>
inline void PrintElementsPos(const T& coll,const char* optcstr="")
{
    typename T::const_iterator pos;

    std::cout<<optcstr;
    for(pos=coll.begin();pos != coll.end(); ++pos)
        std::cout<<&*pos<<" ";

    std::cout<<endl;
}

/*--------------插入int型数据------------------*/
template<class T>
inline void InsertElements(T& coll,int first,int last)
{
    for(int i = first; i<=last; ++i)
        coll.insert(coll.end(),i);
}

void print(int elem)
{
    std::cout<< elem << " ";
}

//for_each对每个元素执行操作
void Learn_for_each()
{
    std::cout<<endl<<"--------------------in Learn for_each()"<<endl;

    vector<int> coll;

    InsertElements(coll,1,9);
    PrintElements(coll,"coll : ");
    std::cout<<"for_each print : ";
    for_each(coll.begin(),coll.end(),
            print);

    std::cout<<endl;

    std::cout<<"每个元素与第一个元素求和"<<endl;
    for_each(coll.begin(),coll.end(),
            FunctionObjectType<int>(*coll.begin()));

    PrintElements(coll,"coll : ");

    std::cout<<endl;
}

bool isEven(int elem)
{
    return elem%2 == 0;
}

void Learn_count()
{
    std::cout<<endl<<"--------------------in Learn count()"<<endl;

    vector<int> coll;

    InsertElements(coll,1,9);
    PrintElements(coll,"coll : ");

    std::cout<<"值为2的个数 : ";
    int num = 0;
    num = count(coll.begin(),coll.end(),
            2);

    std::cout<<num<<endl;

    std::cout<<"偶数的个数 : ";
    num = 0;
    num = count_if(coll.begin(),coll.end(),
            isEven);

    std::cout<<num<<endl;
}

bool absLess(int elem1,int elem2)
{
    return abs(elem1) < abs(elem2);
}

void Learn_mxx_element()
{
    std::cout<<endl<<"--------------------in Learn min_element() max_element()"<<endl;

    vector<int> coll;

    InsertElements(coll,1,9);
    InsertElements(coll,-4,3);

    PrintElements(coll,"coll : ");

    std::cout<<"最小元素 : ";
    std::cout<<*min_element(coll.begin(),coll.end())<<endl;

    std::cout<<"最大元素 : ";
    std::cout<<*max_element(coll.begin(),coll.end())<<endl;

    std::cout<<"绝对值最小元素 : ";
    std::cout<<*min_element(coll.begin(),coll.end(),absLess)<<endl;

    std::cout<<"绝对值最大元素 : ";
    std::cout<<*max_element(coll.begin(),coll.end(),absLess)<<endl;

    std::cout<<endl;
}


template<class T>
class FunctionFindType
{
private:
    T theValue;
public:
    FunctionFindType(const T& v):theValue(v)
    {

    }
public:
    bool operator()(T &i)
    {
        return theValue == abs(i);
    }
};

void Learn_find()
{
    std::cout<<endl<<"--------------------in Learn find() find_if() find_end() "<<endl;

    vector<int> coll;

    InsertElements(coll,1,9);
    InsertElements(coll,-4,3);

    PrintElements(coll,"coll : ");
    PrintElementsPos(coll,"coll pos : ");

    vector<int>::iterator pos;

    std::cout<<"查找值为2的第一元素 : "<<endl;
    pos = find(coll.begin(),coll.end(),
            2);

    std::cout<<"pos : "<<&*pos<<endl<<"value: "<<*pos<<endl;

    std::cout<<"查找值为2的第二元素 : "<<endl;
    pos++;
    pos = find(pos,coll.end(),
                2);

    std::cout<<"pos : "<<&*pos<<endl<<"value: "<<*pos<<endl;

    std::cout<<"查找绝对值相当的第一元素 : "<<endl;
    pos = find_if(coll.begin(),coll.end(),
            FunctionFindType<int>(2));

    std::cout<<"pos : "<<&*pos<<endl<<"value: "<<*pos<<endl;

    std::cout<<"查找绝对值相当的第二元素 : "<<endl;
    pos++;
    pos = find_if(pos,coll.end(),
            FunctionFindType<int>(2));

    std::cout<<"pos : "<<&*pos<<endl<<"value: "<<*pos<<endl;
}

bool checkEven(int elem,bool even)
{
    if(even)
    {
        return elem % 2 == 0;//判断是不是偶数
    }
    else
    {
        return elem % 2 == 1;//判断是不是奇数
    }
}
void Learn_search()
{
    std::cout<<endl<<"--------------------in Learn search_n() search(),find_end()"<<endl;

    vector<int> coll;

    InsertElements(coll,1,1);
    InsertElements(coll,1,1);
    InsertElements(coll,-2,1);
    InsertElements(coll,1,9);
    InsertElements(coll,-4,3);

    PrintElements(coll,"coll : ");
    PrintElementsPos(coll,"coll pos : ");

    vector<int>::iterator pos;

    std::cout<<"查找第一个连续2个1的位置 : "<<endl;
    pos = search_n(coll.begin(),coll.end(),
                            2,
                            1);

    std::cout<<"pos : "<<&*pos<<endl;

    std::cout<<"查找第二个连续2个1的位置 : "<<endl;
    pos++;
    pos = search_n(pos,coll.end(),
                2,
                1);

    std::cout<<"pos : "<<&*pos<<endl;

    vector<int> subcoll;
    InsertElements(subcoll,1,3);
    std::cout<<"查找第一次出现 1，2，3的位置 :"<<endl;
    pos = search(coll.begin(),coll.end(),
                        subcoll.begin(),subcoll.end());
    std::cout<<"pos : "<<&*pos<<"  value: "<<*pos<<endl;

    std::cout<<"查找第二次出现 1，2，3的位置 :"<<endl;
    pos++;
    pos = search(pos,coll.end(),
                        subcoll.begin(),subcoll.end());
    std::cout<<"pos : "<<&*pos<<"  value: "<<*pos<<endl;

    std::cout<<"找出满足‘偶，奇，偶’条件的子序列位置 ："<<endl;
    bool checkEvenArgs[3] = {true,false,true};
    pos = search(coll.begin(),coll.end(),
                        checkEvenArgs,checkEvenArgs + 3,
                        checkEven);

    while(pos != coll.end())
    {
        std::cout<<"pos : "<<&*pos<< "    start value ："<<*pos <<endl;
        pos = search(++pos,coll.end(),
                            checkEvenArgs,checkEvenArgs + 3,
                            checkEven);
    }

    std::cout<<"find_end查找最后一次出现 1，2，3的位置 :"<<endl;
    pos = find_end(coll.begin(),coll.end(),
                        subcoll.begin(),subcoll.end());
    std::cout<<"pos : "<<&*pos<<"  value: "<<*pos<<endl;

    std::cout<<"find_end查找倒数第二次出现 1，2，3的位置 :"<<endl;
    pos = find_end(coll.begin(),pos,
                        subcoll.begin(),subcoll.end());
    std::cout<<"pos : "<<&*pos<<"  value: "<<*pos<<endl;

    subcoll.clear();
    InsertElements(subcoll,3,3);
    InsertElements(subcoll,2,2);

    PrintElements(coll,"coll : ");
    PrintElementsPos(coll,"coll pos : ");
    PrintElements(subcoll,"subcoll : ");
    std::cout<<"find_first_of查找第一个既在coll也在subcoll中出现的元素在coll中的位置 :"<<endl;
    pos = find_first_of(coll.begin(),coll.end(),
                        subcoll.begin(),subcoll.end());
    std::cout<<"pos : "<<&*pos<<"  value: "<<*pos<<endl;

    std::cout<<"adjacent_find查找连续2个元素相等的第1个元素的位置 : "<<endl;
    pos = adjacent_find(coll.begin(),coll.end());
    std::cout<<"pos : "<<&*pos<<"  value: "<<*pos<<endl;
}

void Learn_equal()
{
    std::cout<<endl<<"--------------------in Learn equal() "<<endl;

    vector<int> coll1;
    vector<int> coll2;
    vector<int> coll3;
    InsertElements(coll1,1,9);
    InsertElements(coll2,1,9);
    InsertElements(coll3,1,4);

    PrintElements(coll1,"coll 1 : ");
    PrintElements(coll2,"coll 2 : ");

    if(equal(coll1.begin(),coll1.end(),
            coll2.begin()))
    {
        cout << "coll1 == coll2"<<endl;
    }
    else
    {
        cout<<"coll1 != coll2"<<endl;
    }

    PrintElements(coll1,"coll 1 : ");
    PrintElements(coll3,"coll 3 : ");

    if(equal(coll1.begin(),coll1.end(),
            coll3.begin()))
    {
        cout << "coll1 == coll3"<<endl;
    }
    else
    {
        cout<<"coll1 != coll3"<<endl;
    }
}

void Learn_mismatch()
{
    std::cout<<endl<<"--------------------in Learn mismatch() "<<endl;

    vector<int> coll1;
    vector<int> coll2;
    vector<int> coll3;
    InsertElements(coll1,1,9);
    InsertElements(coll2,1,3);
    InsertElements(coll2,6,6);

    PrintElements(coll1,"coll 1 : ");
    PrintElements(coll2,"coll 2 : ");

    pair<vector<int>::iterator,vector<int>::iterator> values;
    std::cout<<"返回第一组两两相异的对应元素："<<endl;
    values = mismatch(coll1.begin(),coll1.end(),
                                 coll2.begin());
    if(values.first == coll1.end())
    {
        cout<<"no mismatch"<<endl;
    }
    else
    {
        cout <<"first mismatch : "
                <<*values.first << " and "
                <<*values.second <<endl;
    }
}

int main()
{
    cout<<"hello world"<<endl;

    //--------------------算法--------begin
    //for_each
    Learn_for_each();

    //count,count_if
    Learn_count();

    //min_element,max_element
    Learn_mxx_element();

    //find find
    Learn_find();

    //search
    Learn_search();

    //equal
    Learn_equal();

    //mismatch
    Learn_mismatch();
    cin.get();

    return 0;
}