C++,stl，常用排序算法，常用拷贝和替换算法-编程知识

C++,stl，常用排序算法，常用拷贝和替换算法

1.常用排序算法

sort

random_shuffle

merge

reverse

2.常用拷贝和替换算法

copy

replace

replace_if

swap

1.常用排序算法

sort

默认从小到大排序

#include<bits/stdc++.h>
using namespace std;int main()
{vector<int> v;v.push_back(1);v.push_back(2);v.push_back(9);v.push_back(2);v.push_back(4);sort(v.begin(),v.end());for(auto &ele:v){cout << ele << ' ';}sort(v.begin(),v.end(),greater<int>());//降序排列cout << endl;for(auto &ele:v){cout << ele << ' ';}return 0;
}

random_shuffle

使用的时候要加随机数种子

#include<bits/stdc++.h>
using namespace std;void print(int v)
{cout << v << ' ';
}int main()
{srand((unsigned int)time(NULL));vector<int> v;v.push_back(1);v.push_back(2);v.push_back(9);v.push_back(2);v.push_back(4);for_each(v.begin(),v.end(),print);cout << endl;random_shuffle(v.begin(),v.end());for_each(v.begin(),v.end(),print);return 0;
}

merge

#include<bits/stdc++.h>
using namespace std;void print(int v)
{cout << v << ' ';
}int main()
{vector<int> v1;v1.push_back(1);v1.push_back(2);v1.push_back(9);v1.push_back(2);v1.push_back(4);sort(v1.begin(),v1.end());vector<int> v2;for(int i = 2; i <= 6; i += 2){v2.push_back(i);}vector<int> v;v.resize(v1.size() + v2.size());//必须v1，v2都是升序或者都是降序merge(v1.begin(),v1.end(),v2.begin(),v2.end(),v.begin());for_each(v.begin(),v.end(),print);return 0;
}

reverse

#include<bits/stdc++.h>
using namespace std;void print(int v)
{cout << v << ' ';
}int main()
{vector<int> v1;v1.push_back(1);v1.push_back(2);v1.push_back(9);v1.push_back(2);v1.push_back(4);for_each(v1.begin(),v1.end(),print);cout << endl;reverse(v1.begin(),v1.end());cout << "反转后" << endl;for_each(v1.begin(),v1.end(),print);return 0;
}

2.常用拷贝和替换算法

copy

#include<bits/stdc++.h>
using namespace std;void print(int v)
{cout << v << ' ';
}int main()
{vector<int> v1;v1.push_back(1);v1.push_back(2);v1.push_back(9);v1.push_back(2);v1.push_back(4);for_each(v1.begin(),v1.end(),print);cout << endl;vector<int> v2;v2.resize(v1.size());copy(v1.begin(),v1.end(),v2.begin());cout << "复制后" << endl;for_each(v2.begin(),v2.end(),print);return 0;
}

replace

#include<bits/stdc++.h>
using namespace std;void print(int v)
{cout << v << ' ';
}int main()
{vector<int> v1;v1.push_back(1);v1.push_back(2);v1.push_back(9);v1.push_back(2);v1.push_back(4);for_each(v1.begin(),v1.end(),print);cout << endl;cout << "替换后" << endl;replace(v1.begin(),v1.end(),2,1000);for_each(v1.begin(),v1.end(),print);return 0;
}

replace_if

#include<bits/stdc++.h>
using namespace std;class print
{
public:void operator()(int v){cout << v << ' ';}
};class dayu2
{
public:bool operator()(int v){return v > 2;}
};int main()
{vector<int> v1;v1.push_back(1);v1.push_back(2);v1.push_back(9);v1.push_back(2);v1.push_back(4);for_each(v1.begin(),v1.end(),print());cout << endl;cout << "替换后" << endl;replace_if(v1.begin(),v1.end(),dayu2(),999);for_each(v1.begin(),v1.end(),print());return 0;
}

swap

交换的容器要是同种类型

#include<bits/stdc++.h>
using namespace std;class print
{
public:void operator()(int v){cout << v << ' ';}
};int main()
{vector<int> v1;v1.push_back(1);v1.push_back(2);v1.push_back(9);v1.push_back(2);v1.push_back(4);vector<int> v2;for(int i = 1; i <= 3; i++){v2.push_back(i);}cout << "交换前" << endl;for_each(v1.begin(),v1.end(),print());cout << endl;for_each(v2.begin(),v2.end(),print());cout << endl << "交换后" << endl;swap(v1,v2);for_each(v1.begin(),v1.end(),print());cout << endl;for_each(v2.begin(),v2.end(),print());return 0;
}