#include <algorithm>

1 adjacent_find

查找重复的元素

2 find_if

查找符合条件的第一个元素

3 find_if_not

查找不符合条件的第一个元素

4 for_each

可以遍历每一个元素

5 partial_sort

部分排序

6 partition

服务于快速排序法的分区

7 prev_permutation

排序

8 random_shuffle

随机排序

9 rotate

旋转

adjacent_find

查找重复的元素

 #include <iostream>
 #include <algorithm>
 #include <set>

 void main()
 {
     std::multiset<int>myset;

     myset.insert();
     myset.insert();
     myset.insert();
     myset.insert();
     myset.insert();

     auto it = adjacent_find(myset.begin(), myset.end());

     std::cout << *it << std::endl;

     it = adjacent_find(it++, myset.end());

     std::cout << *it << std::endl;

     it = adjacent_find(it++, myset.end());

     std::cout << *it << std::endl;
 }

find

 1 #include <iostream>
 2 #include <algorithm>
 3 #include <vector>
 4
 5 void main()
 6 {
 7     std::vector<int>myv;
 8
 9     myv.push_back(1);
10     myv.push_back(2);
11     myv.push_back(3);
12
13     auto i = find_if(myv.begin(), myv.end(), [](int v)->bool {return v < 4; });//返回第一个小于4的元素
14
15     if (i == myv.end())
16     {
17         std::cout << "not found" << std::endl;
18     }
19     else
20     {
21         std::cout << *i << std::endl;
22     }
23 }

find_if

查找符合条件的第一个元素

 1 #include <iostream>
 2 #include <algorithm>
 3 #include <vector>
 4
 5 void main()
 6 {
 7     std::vector<int>myv;
 8
 9     myv.push_back(1);
10     myv.push_back(2);
11     myv.push_back(3);
12
13     auto i = find_if(myv.begin(), myv.end(), [](int v)->bool {return v < 4; });//返回第一个小于4的元素
14
15     if (i == myv.end())
16     {
17         std::cout << "not found" << std::endl;
18     }
19     else
20     {
21         std::cout << *i << std::endl;
22     }
23 }

find_if_not

查找不符合条件的第一个元素

 1 #include <iostream>
 2 #include <algorithm>
 3 #include <vector>
 4
 5 void main()
 6 {
 7     std::vector<int>myv;
 8
 9     myv.push_back(1);
10     myv.push_back(2);
11     myv.push_back(3);
12
13     auto i = find_if_not(myv.begin(), myv.end(), [](int v)->bool {return v < 4; });//返回第一个不是小于4的元素
14
15     if (i == myv.end())
16     {
17         std::cout << "not found" << std::endl;
18     }
19     else
20     {
21         std::cout << *i << std::endl;
22     }
23 }

//[地址](参数) {语句; }

//&res直接操作一个变量，res等价于返回值，x代表参数，每次充当迭代器指向的元素

//不仅仅适用于array，也适用于vector

vector使用for_each

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

 void main()
 {
     std::vector<int>myvector;//创建一个数组，数组元素是int类型

     myvector.push_back();//尾部插入
     myvector.push_back();
     myvector.push_back();

     int res = ;//保存结果

     //[地址](参数) {语句; }
     //&res直接操作一个变量，res等价于返回值，x代表参数，每次充当迭代器指向的元素
     //不仅仅适用于array，也适用于vector
     for_each(myvector.begin(), myvector.end(), [&res](int x) {res += x; });

     std::cout << res;//打印

     system("pause");
 }

普通数组使用for_each

 #include <iostream>
 #include <algorithm>

 struct print
 {
     void operator ()(int x)//重载()
     {
         std::cout << x << std::endl;
     }
 };

 void printA(int x)
 {
     std::cout << x << std::endl;
 }

 int main()
 {
     int a[] = { ,,,,,,,,, };
     int *p = std::find(a, a + , );

     std::cout << a << " " << a +  << std::endl;
     std::cout << *p << std::endl;

     if (p == a + )
     {
         printf("没有找到\n");
     }

     std::for_each(a, a + , print());//第三个参数是函数指针，必须是函数类型
     std::for_each(a, a + , printA);

     return ;
 }

5 partial_sort

部分排序

 #include <iostream>
 #include <algorithm>
 #include <string>
 #include <vector>

 struct student
 {
 public:
     std::string name;
     int score;
 public:
     student(std::string str, int num) :name(str), score(num)
     {

     }
     bool operator<(const student &s1)const
     {
         return this->score < s1.score;
     }
 };

 void main()
 {
     std::vector<student>ss;

     {
         student s1("AA", );
         ss.push_back(s1);
     }

     {
         student s1("BB", );
         ss.push_back(s1);
     }

     {
         student s1("CC", );
         ss.push_back(s1);
     }

     {
         student s1("DD", );
         ss.push_back(s1);
     }

     partial_sort(ss.begin(), ss.begin() + , ss.end());

     for (int i = ; i < ; i++)
     {
         std::cout << ss[i].name << " " << ss[i].score << std::endl;
     }
 }

partition

服务于快速排序法的分区

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

 template <class T>
 struct show
 {
 public:
     void operator()(T &t)
     {
         std::cout << t << " ";
     }
 };

 bool isok(int num)
 {
     return num == ;
 }

 void main()
 {
     std::vector<int>myv;

     for (int i = ; i < ; i++)
     {
         myv.push_back(i);
     }

     for_each(myv.begin(), myv.end(), show<int>());
     std::cout << std::endl;

     partition(myv.begin(), myv.end(), isok);

     for_each(myv.begin(), myv.end(), show<int>());
     std::cout << std::endl;
 }

prev_permutation

排序

 #include <iostream>
 #include <algorithm>

 void main()
 {
     int a[] = { ,,, };

     do
     {
         std::cout << a[] << " " << a[] << " " << a[] << " " << a[] << std::endl;
     } while (std::prev_permutation(a, a + ));
 }

random_shuffle

随机排序

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

 template <class T>
 struct show
 {
 public:
     void operator()(T &t)
     {
         std::cout << t << " ";
     }
 };

 void main()
 {
     std::vector<int>myv;

     for (int i = ; i < ; i++)
     {
         myv.push_back(i);
     }

     for_each(myv.begin(), myv.end(), show<int>());
     std::cout << std::endl;

     random_shuffle(myv.begin(), myv.end());//随机排序

     for_each(myv.begin(), myv.end(), show<int>());
     std::cout << std::endl;

     random_shuffle(myv.begin(), myv.end());//随机排序

     for_each(myv.begin(), myv.end(), show<int>());
     std::cout << std::endl;
 }

rotate

旋转

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

 template <class T>
 struct show
 {
 public:
     void operator()(T &t)
     {
         std::cout << t << " ";
     }
 };

 bool isok(int num)
 {
     return num == ;
 }

 void main()
 {
     std::vector<int>myv;

     for (int i = ; i < ; i++)
     {
         myv.push_back(i);
     }

     for_each(myv.begin(), myv.end(), show<int>());
     std::cout << std::endl;

     rotate(myv.begin(), myv.begin() + , myv.end());

     for_each(myv.begin(), myv.end(), show<int>());
     std::cout << std::endl;

     rotate(myv.begin(), myv.begin() + , myv.end());

     for_each(myv.begin(), myv.end(), show<int>());
     std::cout << std::endl;
 }