标签：begin end cout STL back C++ int 算法 L1
文章目录
一、基本概念
算法是STL中很重要的一部分，其功能包括比较，查找，排序，交换，遍历，复制等等。
最大的算法头文件是algorithm,封装了很多种模板类。还有numeric和functional也比较常见。
二、程序示例
1.遍历
#include<iostream>
#include<list>
#include<algorithm>
using namespace std;
void print(int a)
{
cout << a << " ";
}
class print1
{
public:
void operator()(int a)
{
cout << a << " ";
}
};
class print2
{
public:
int operator()(int a)
{
cout << a << " ";
return a;
}
};
void test()
{
list<int>L;
L.push_back(1);
L.push_back(2);
L.push_back(3);
//函数作为形参进行遍历输出
for_each(L.begin(), L.end(), print);
cout << endl;
//仿函数进行遍历
for_each(L.begin(), L.end(), print1());
cout << endl;
//transform实现遍历
list<int>L1;
L1.resize(L.size());
transform(L.begin(),L.end(),L1.begin(), print2());
}
int main()
{
test();
system("pause");
}
2. 查找
#include<iostream>
#include<list>
#include<algorithm>
using namespace std;
class Compare
{
public:
//一元谓词
bool operator()(int a)
{
return a > 1;
}
};
class Cat
{
public:
Cat(string name, int color, int age)
{
this->Name = name;
this->Color = color;
this->Age = age;
}
//自定义数据类型需要重载==
bool operator==(const Cat& cat)
{
if (Name == cat.Name && Color == cat.Color && Age == cat.Age)
{
return true;
}
else
{
return false;
}
}
public:
string Name;
int Color;
int Age;
};
class print1
{
public:
bool operator()(Cat& cat)
{
return cat.Age > 3;
}
};
void test()
{
list<int>L;
L.push_back(1);
L.push_back(2);
L.push_back(3);
//find算法查找
list<int>::iterator i = find(L.begin(), L.end(), 1);
if (i == L.end())
{
cout << "未查找到" << endl;
}
else
{
cout << "查找到" << *i<<endl;
}
//find_if查找
list<int>::iterator i1 = find_if(L.begin(),L.end(),Compare());
if (i1 == L.end())
{
cout << "未查找到" << endl;
}
else
{
cout << "查找到" << *i1 << endl;
}
//查找元素是否存在,无序序列结果未知
bool i2 = binary_search(L.begin(), L.end(), 1);
if (i2)
{
cout << "查找到1" << endl;
}
else
{
cout << "未查找到" << endl;
}
//count统计
int n = count(L.begin(), L.end(),1);
cout << n << endl;
//count_if统计
int n1 = count_if(L.begin(), L.end(), Compare());
cout << n1 << endl;
}
void test1()
{
list<Cat>L;
Cat cat1("小100", 76, 2);
Cat cat2("小200", 32, 2);
Cat cat3("小300", 32, 4);
Cat cat4("小400", 32, 3);
Cat cat5("小500", 54, 1);
//插入
L.push_back(cat1);
L.push_back(cat2);
L.push_back(cat3);
L.push_back(cat4);
L.push_back(cat5);
//find查找
list<Cat>::iterator i = find(L.begin(), L.end(), cat1);
if (i == L.end())
{
cout << "未查找到" << endl;
}
else
{
cout << "查找到" << (*i).Name << endl;
}
//find_if查找
list<Cat>::iterator i1 = find_if(L.begin(), L.end(), print1());
if (i1 == L.end())
{
cout << "未查找到" << endl;
}
else
{
cout << "查找到" << (*i1).Name << endl;
}
//查找相邻的重复元素
list<Cat>::iterator i2 = adjacent_find(L.begin(), L.end());
if (i2 == L.end())
{
cout << "未查找到" << endl;
}
else
{
cout << "查找到" << (*i2).Name << endl;
}
Cat cat6("小300", 32, 4);
//count统计，需要重载
int n = count(L.begin(), L.end(), cat6);
cout << n << endl;
}
int main()
{
test1();
system("pause");
}
3. 排序、拷贝、替换
#include<iostream>
#include<vector>
#include<algorithm>
#include<ctime>
using namespace std;
class Compare
{
public:
//一元谓词
bool operator()(int a,int b)
{
return a > b;
}
};
class Compare3
{
public:
//一元谓词
bool operator()(int a)
{
return a > 3;
}
};
void print(int a)
{
cout << a << " ";
}
class Cat
{
public:
Cat(string name, int color, int age)
{
this->Name = name;
this->Color = color;
this->Age = age;
}
//自定义数据类型需要重载==
bool operator==(const Cat& cat)
{
if (Name == cat.Name && Color == cat.Color && Age == cat.Age)
{
return true;
}
else
{
return false;
}
}
public:
string Name;
int Color;
int Age;
};
void test()
{
vector<int>L;
L.push_back(1);
L.push_back(2);
L.push_back(3);
L.push_back(4);
//降序
sort(L.begin(), L.end(),Compare());
for_each(L.begin(), L.end(), print);
cout << endl;
//greater<int>()
sort(L.begin(), L.end(),greater<int>());
for_each(L.begin(), L.end(), print);
cout << endl;
sort(L.begin(), L.end());
//随机打乱
//srand((unsigned int)time(NULL));
//random_shuffle(L.begin(), L.end());
//for_each(L.begin(), L.end(), print);
//cout << endl;
vector<int>L1(L);
vector<int>L2;
L2.resize(L.size()+L1.size());
//合并,默认只能同为升序的合并merge必须为有序序列
merge(L.begin(), L.end(), L1.begin(), L1.end(),L2.begin());
for_each(L2.begin(), L2.end(), print);
cout << endl;
//反转
reverse(L.begin(), L.end());
for_each(L.begin(), L.end(), print);
cout << endl;
//拷贝
vector<int>L3;
L3.resize(L.size());
copy(L.begin(), L.end(), L3.begin());
for_each(L3.begin(), L3.end(), print);
cout << endl;
//替换
replace(L.begin(), L.end(), 2, 5);
for_each(L.begin(), L.end(), print);
cout << endl;
replace_if(L.begin(), L.end(), Compare3(),20);
for_each(L.begin(), L.end(), print);
cout << endl;
//互换
swap(L, L1);
}
int main()
{
test();
system("pause");
}
4. numeric相关算法
#include<iostream>
#include<vector>
#include<numeric>
#include<algorithm>
#include<ctime>
using namespace std;
void print(int a)
{
cout << a << " ";
}
void test()
{
vector<int>L;
L.push_back(1);
L.push_back(2);
L.push_back(3);
L.push_back(4);
//计算容器元素的和，0为起始累加值
int total = accumulate(L.begin(), L.end(), 0);
cout << total<<endl;
//填充元素
vector<int>L1;
L1.resize(L.size());
fill(L1.begin(), L1.end(), 3);
for_each(L1.begin(), L1.end(), print);
cout << endl;
//求交集
vector<int>L2;
L2.resize(min(L.size(),L1.size()));
vector<int>::iterator i = set_intersection(L.begin(), L.end(), L1.begin(), L1.end(), L2.begin());
for_each(L2.begin(), i, print);
cout << endl;
//求并集
vector<int>L3;
L3.resize(L.size()+ L1.size());
vector<int>::iterator j = set_union(L.begin(), L.end(), L1.begin(), L1.end(), L3.begin());
for_each(L3.begin(), j, print);
cout << endl;
//差集
vector<int>L4;
L4.resize(max(L.size() , L1.size()));
vector<int>::iterator j1 = set_difference(L.begin(), L.end(), L1.begin(), L1.end(), L4.begin());
for_each(L4.begin(), j1, print);
}
int main()
{
test();
system("pause");
}
总结
以上只是stl算法中常见的，后续会随时补充新的算法。
标签：begin,end,cout,STL,back,C++,int,算法,L1 来源： https://blog.csdn.net/baidu_35536188/article/details/122925045
本站声明： 1. iCode9 技术分享网（下文简称本站）提供的所有内容，仅供技术学习、探讨和分享； 2. 关于本站的所有留言、评论、转载及引用，纯属内容发起人的个人观点，与本站观点和立场无关； 3. 关于本站的所有言论和文字，纯属内容发起人的个人观点，与本站观点和立场无关； 4. 本站文章均是网友提供，不完全保证技术分享内容的完整性、准确性、时效性、风险性和版权归属；如您发现该文章侵犯了您的权益，可联系我们第一时间进行删除； 5. 本站为非盈利性的个人网站，所有内容不会用来进行牟利，也不会利用任何形式的广告来间接获益，纯粹是为了广大技术爱好者提供技术内容和技术思想的分享性交流网站。