C++stl简单使用

//1.sort函数排序
/*
#include <iostream>
#include <algorithm>
using namespace std;
int main()
{
  int a[] = { 2,0,3,1,8,2,4,0 };
  sort(a, a + 3);//对前三个数排序
  for (int i=0;i<8;++i)
  {
    cout << a[i] << " ";
  }
  return 0;
}*/
//2.字符串处理
/*
#include <iostream>
#include <string>
using namespace std;
int main()
{
  string s = "hello world!";
  cout<<s<<endl;
  string a;
  getline(cin, a);//获取一行数据
  cout << a << endl;
  return 0;
}*/
/*
#include <iostream>
#include <string>
#include <algorithm>
using namespace std;
int main()
{
  string s;
  s += "小明";
  s =s+"小红";
  int a = 5;
  s += (a + '0');//把a加入到字符串中
  cout << s << endl;
  string x = "741852";
  sort(x.begin(),x.end());//排序
  cout << x << endl;
  string n = "7a4185b2";
  n.erase(n.begin());//删除第一个元素
  n.erase(--n.end());//删除最后一个元素
  cout << n << endl;
  string m = "147258369";
  m = m.substr(2, 5);//取72583,从2位置开始往后面截断5个
  cout << m<<endl;
  m = m.substr(2, -1);//索引为2,截断到最后
  cout << m << endl;
  return 0;
}*/
//循环
/*
#include <iostream>
using namespace std;
int main()
{
  string s="147258369";
  for (int i=0;i<s.length();++i)
  {
    cout <<s[i] ;
  }
  cout << endl;
  //迭代器
  for (string ::iterator it=s.begin();it!=s.end();++it)
  {
    cout << *it;
  }
  cout << endl;
    //迭代器化简
  for (auto it=s.begin();it!=s.end();++it)
  {
    cout << *it;
  }
  cout << endl;
  //C++11新特性
  for (auto x:s)
  {
    cout << x;
  }
  return 0;
}*/
//3.vector.vector相当于数组，模板类型相当于存放的内容
/*
#include <iostream>
#include <vector>
using namespace std;
int main()
{
  //1.vector构造
  vector <int> v0;//定义一个空的vector
  vector<int> v2(4);//定义一个4个大小的vector,初始为0
  for (auto x:v2)
  {
    cout << x;
  }
  cout << endl;
  vector<int> v3(4, 6);//定义一个4个大小的vector,初始值为6
  for (int i=0;i<v3.size();++i)
  {
    cout << v3[i];
  }
  cout << endl;
  vector<int> v{ 8,2,3,4,5 };//定义一个vector,数字为1,2,3,4,5
  for (auto it=v.begin();it!=v.end();++it)
  {
    cout << *it;
  }
  cout << endl;
  cout << v[1];//取索引为1的元素
  cout << endl;
  cout << v.at(2);//取索引为1的元素
  return 0;
}*/
/*
#include <iostream>
#include <vector>
using namespace std;
int main()
{
  //push_back追加内容
  vector <int> v;
  v.push_back(1);
  v.push_back(2);
  v.push_back(3);
  v.push_back(4);
  v.push_back(6);
  for (int i=0;i<v.size();++i)
  {
    cout << v[i];
  } 
  cout << endl;
  v.resize(10);//进行重置大小,不赋值默认为0
  for (int i = 0; i < v.size(); ++i)
  {
    cout << v[i];
  }
  cout << endl;
  v.erase(v.begin());
  v.erase(--v.end());
  for (int i = 0; i < v.size(); ++i)
  {
    cout << v[i];
  }
  return 0;
}*/
/*
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main()
{
  //push_back追加内容
  vector <int> v;
  v.push_back(1);
  v.push_back(2);
  v.push_back(3);
  v.push_back(4);
  v.push_back(6);
  cout << v.front()<<" ";//获取第一个元素
  cout << v[0]<<" ";
  cout << *v.begin()<<" ";
  cout << v.back()<<" ";//获取最后一个元素
  cout << v[v.size()-1]<<" ";
  cout << *--v.end()<<endl;
  //排序
  //vector<int> v{ 1, 4,  7, 2, 5, 8, 3, 6, 9 };
  sort(v.begin(), v.end(), less<int>());//从小到大排列
  for (auto x : v)
  {
    cout << x;
  }
  cout << endl;
  sort(v.begin(), v.end(), greater<int>());//从大到小排列
  for (int i=0;i<v.size();++i)
  {
    cout << v[i];
  }
  return 0;
}*/
//4.栈
/*
#include <iostream>
#include <stack>
using namespace std;
int main()
{
  stack<int> s;
  //s.push(1);
  s.push(2);
  s.push(3);
  s.push(4);
  s.push(5);
  cout << s.top() << endl;
  s.pop();
  cout << s.top() << endl;
  cout << s.size() << endl;
  bool a = s.empty();
  cout << a << endl;
  return 0;
}*/
//进制转换(十转二)
/*
#include <iostream>
#include <stack>
using namespace std;
int itob(int decimal)
{
  stack<int> s;
  int res = 0;
  while (decimal!=0)
  {
    s.push(decimal % 2);
    decimal /= 2;
  }
  while (!s.empty())
  {
    res = res * 10 + s.top();
    s.pop();
  }
  return res;
}
int main()
{
  int n;
  cin >> n;
  cout << itob(n);
  return 0;
}*/
//输入一行字符串，将字符串逆序打印
//输入：hello world
//输出：world hello
/*
#include <iostream>
#include <stack>
#include <sstream>
using namespace std;
int main()
{
  string str;
  stack<string> s;
  getline(cin, str);
  stringstream ss;
  ss << str;
  while (ss>>str)
  {
    s.push(str);
  }
  while (!s.empty())
  {
    cout << s.top();
    s.pop();
    if (s.size() != 0) cout << " ";
  }
  return 0;
}*/
/*#include <iostream>
#include <stack>
#include <sstream>
using namespace std;
int main()
{
  //1.字符串转数字
  string s = "123456";
  int i;
  stringstream ss;
  ss << s; // 将string类型的值放入输入流中
  ss >> i;// 从sstream中抽取前面插入的string类型的值，赋给int类型
  cout << i << endl;
  //方法2
  string a = "123455";
  int b = stoi(a);
  cout << b << endl;
  //数字转字符串
  int c = 1234;
  string out;
  stringstream aa;
  aa << c;
  aa >> out;
  cout << out << endl;
  //方法2
  int d=23123456;
  cout << to_string(d) << endl;
  return 0;
}*/
//4.队列
/*
#include<iostream>
#include<queue>
using namespace std;
int main()
{
  queue<int> q;
  q.push(5);
  q.push(6);
  q.push(7);
  cout << q.front() << endl;
  cout << q.size() << endl;
  return 0;
}*/
/*
#include<iostream>
#include <map>//树状表
using namespace std;
int main()
{
  map<int, int> m;//有序的,树状结构
  m[6] = 3;
  m[5] = 8;
  m[4] = 9;
  for (auto it=m.begin();it!=m.end();it++)
  {
    cout << it->first << " " << it->second << endl;
  }
  for (auto tmp : m)
  {
    cout << tmp.first << " " << tmp.second << endl;
  }
  return 0;
}*/
/*
#include<iostream>
#include <unordered_map>//哈希表
using namespace std;
int main()
{
  unordered_map<int, int> m;//无序的
  m[6] = 3;
  m[5] = 8;
  m[4] = 9;
  m[2] = 6;
  m[1] = 0;
  for (auto it = m.begin(); it != m.end(); it++)
    cout << it->first << " " << it->second << endl;
  for (auto tmp : m) {
    cout << tmp.first << " " << tmp.second << endl;
  }
  return 0;
}*/
//pair的用法,将map转成vector进行排序
/*
#include<iostream>
#include <unordered_map>//哈希表
#include <algorithm>
using namespace std;
bool cmp(pair<int, int> a, pair<int, int> b)
{
  return a.first > b.first;
}
int main()
{
  unordered_map<int, int> m;//无序的
  m[4] = 9;
  m[2] = 6;
  m[6] = 3;
  m[5] = 8;
  m[1] = 0;
  vector<pair<int, int>> v(m.begin(), m.end());
  sort(v.begin(), v.end(), cmp);
  for (auto tmp : v) {
    cout << tmp.first << tmp.second << endl;
  }
  return 0;
}*/
//集合,计数去重
/*
#include<iostream>
#include <set>
#include <unordered_set>
using namespace std;
int main()
{
  set<int> s;//树状结构,有序
  unordered_set<int> s2;//哈希结构,无序,快
  s.insert(3);
  s.insert(4);
  s.insert(4);
  s.insert(4);
  s.insert(5);
  cout << s.size() << endl;
  for (auto tmp:s)
  {
    cout << tmp << " ";
  }
  cout << endl;
  for (auto it=s.begin();it!=s.end();++it)
  {
    cout << *it << " ";
  }
  cout << endl;
  return 0;
}*/
//deque双端队列
/*
#include<iostream>
#include <deque>
#include <algorithm>
using namespace std;
int main()
{
  deque<int> d;
  //4 9 1 2
  d.push_back(1);
  d.push_back(6);
  d.push_back(5);
  d.push_back(7);
  d.push_back(2);
  d.push_front(9);
  d.push_front(5);
  d.push_front(3);
  d.push_front(6);
  d.push_front(4);
  d.pop_back();
  d.pop_front();
  for (auto tmp:d)
  {
    cout << tmp <<" ";
  }
  cout << endl;
  sort(d.begin(), d.end(), greater<int>());
  for (auto it=d.begin();it!=d.end();++it)
  {
    cout << *it <<" ";
  }
  cout << endl;
  return 0;
}*/
//list双向链表
#include<iostream>
#include <list>
using namespace std;
int main()
{
  list<int> li;
  li.push_back(6);
  li.push_front(5);
  li.emplace_front(9);//在开头添加元素
  li.emplace_back(10);
  li.insert(++li.begin(), 2);
  for (auto tmp:li)
  {
    cout << tmp << " ";
  }
  cout << endl;
  for (auto it = li.begin(); it != li.end(); it++) cout << *it << endl;
  return 0;
}