当前位置： 首页 > news >正文

05 英雄C++ STL 编程（下）

news 来源：原创 2025/6/10 4:52:53

7、set

7.1 基础概念

容器特点：

#include <iostream>
#include <set>
using namespace std;

int main() {
    set<int> s;
    multiset<int> ms;

    return 0;
}

7.2 对象创建

#include<iostream>
#include<set>
using namespace std;

void printSet(const set<int>& s) {
    for (set<int>::const_iterator it = s.begin(); it != s.end(); it++) {
        cout << *it << " ";
    }
    cout << endl;
}

int main() {
    // 1.默认构造函数
    set<int> s1;
    cout << "s1: ";
    printSet(s1);//空

    // 2. 初始化列表
    set<int> s2_1 = { 9,8,7,6,5 };
    cout << "s2_1: ";
    printSet(s2_1);//5 6  7 8 9

    set<int> s2_2({ 9,8,7,7,6,5 });  // set不支持重复元素、multiset支持重复元素
    cout << "s2_2: ";
    printSet(s2_2);//5 6 7 8 9

    // 3. 迭代器的方式
    set<int> s3(s2_1.begin(), s2_1.end());
    cout << "s3: ";
    printSet(s3);//5 6 7 8 9

    // 4. 拷贝构造
    set<int> s4(s2_2);
    cout << "s4: ";
    printSet(s4);//5 6 7 8 9

    return 0;
}

7.3 赋值操作

#include <iostream>
#include <set>
using namespace std;

void printSet(const set<int>& s) {
    for (set<int>::const_iterator it = s.begin(); it != s.end(); it++) {
        cout << *it << " ";
    }
    cout << endl;
}

int main() {
    set<int> s = { 9,8,5,2,1,1 };
    cout << "s: ";
    printSet(s);// 1 2 5 8 9

    // 1. = set 对象
    set<int> s1;
    s1 = s;//运算符重载
    cout << "s1: ";
    printSet(s1);// 1 2 5 8 9

    // 2. = 初始化列表
    set<int> s2;
    s1 = (s2 = { 3, 4, 5 });
    cout << "s2: ";
    printSet(s2);//3 4 5
    cout << "s1: ";
    printSet(s1);//3 4 5

    return 0;
}

7.4 大小操作

#include<iostream>
#include<set>
using namespace std;

void printSet(const set<int>& s) {
    for (set<int>::const_iterator it = s.begin(); it != s.end(); it++) {
        cout << *it << " ";
    }
    cout << endl;
}

int main() {
    set<int> s1;
    cout << "s1.empty() = " << s1.empty() << endl;//1
    cout << "s1.size()  = " << s1.size() << endl;//0

    set<int> s2 = { 1,1,1,1,6,7,8,9 };
    cout << "s2.empty() = " << s2.empty() << endl;//0
    cout << "s2.size()  = " << s2.size() << endl;//5

    return 0;
}

7.5 数据插入

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

void printSet(const set<int>& s) {
    for (set<int>::const_iterator it = s.begin(); it != s.end(); it++) {
        cout << *it << " ";
    }
    cout << endl;
}

int main() {
    set<int> s;

    // O(logn)

    s.insert(3); printSet(s);//3
    s.insert(2); printSet(s);//2 3
    s.insert(5); printSet(s);//2 3 5
    s.insert(4); printSet(s);//2 3 4 5
    s.insert(1); printSet(s);//1 2 3 4 5

    vector<int> v = { 0, 5, 6, 9 ,8 };
    s.insert(v.begin(), v.end());
    printSet(s);//0 1 2 3 4 5 6 8 9
    return 0;
}

7.6 数据查找

#include<iostream>
#include<set>
using namespace std;

void printSet(const set<int>& s) {
    for (set<int>::const_iterator it = s.begin(); it != s.end(); it++) {
        cout << *it << " ";
    }
    cout << endl;
}

int main() {
    set<int> s = { 1,2,3,4,5 };

    set<int>::iterator it = s.find(3);
    if (it != s.end()) {
        cout << "find: " << (*it) << endl;
    }
    it = s.find(10);
    if (it == s.end()) {
        cout << "can't find: 10" << endl;
    }

    return 0;
}

7.7 数据删除

#include<iostream>
#include<set>
using namespace std;

void printSet(const set<int>& s) {
    for (set<int>::const_iterator it = s.begin(); it != s.end(); it++) {
        cout << *it << " ";
    }
    cout << endl;
}

int main() {
    set<int> s = { 1,2,3,4,5 };
    s.erase(3);
    printSet(s);//1 2 4 5

    set<int>::iterator rm = s.find(4);
    if (rm != s.end()) {
        s.erase(rm);
    }
    printSet(s);//1 2 5
    // [   )
    s = { 1,2,3,4,5 };
    set<int>::iterator rml = s.find(2);
    set<int>::iterator rmr = s.find(4);
    s.erase(rml, rmr);//[rml,rmr)
    printSet(s);//1 4 5
   // cout << *rml << endl;//报错

    return 0;
}

7.8 数据统计

#include<iostream>
#include<set>
using namespace std;

/*
count
*/

void printSet(const set<int>& s) {
    for (set<int>::const_iterator it = s.begin(); it != s.end(); it++) {
        cout << *it << " ";
    }
    cout << endl;
}

void printMultiSet(const multiset<int>& s) {
    for (multiset<int>::const_iterator it = s.begin(); it != s.end(); it++) {
        cout << *it << " ";
    }
    cout << endl;
}

int main() {
    set<int> s = { 1,2,3,4,5 };
    for (int i = 0; i < 8; i += 2) {
        cout << "元素：" << i << "的出现次数为 " << s.count(i) << endl;  // s.has(i)
    }
    multiset<int> ms = { 1,1,1,1,1,1,4,4,4,4,4,2,2,2,2,2,2,2,6,6,6,6,6,8,8,8,5,5,5,5,5 };
    for (int i = 0; i < 8; i += 2) {
        cout << "元素：" << i << "的出现次数为 " << ms.count(i) << endl;
    }
    printMultiSet(ms);//1 1 1 1 1 1 2 2 2 2 2 2 2 4 4 4 4 4 5 5 5 5 5 6 6 6 6 6 8 8 8

    return 0;
}

7.9 排序规则

#include <iostream>
#include <set>
using namespace std;

class CGaGa {
public:
    CGaGa() {
        _name = "";
        _priority = -1;
    }
    CGaGa(string name, int pri) : _name(name), _priority(pri) {}

    //bool operator<(const CGaGa& cgg) const { //外层的const保证 _name和_priority不被修改
    //    return _priority < cgg._priority;
    //}
    void print() const {
        cout << "(" << _priority << ")" << _name << endl;
    }
private:
    string _name;
    int _priority;//优先级
};

int main() {
    set< CGaGa > s;
    s.insert(CGaGa("C++算法零基础", 5));
    s.insert(CGaGa("C++面向对象", 2));
    s.insert(CGaGa("C++零基础语法", 1));
    s.insert(CGaGa("C++数据结构", 3));
    s.insert(CGaGa("C++STL", 4));
    s.insert(CGaGa("C++项目实战(贪食蛇、扫雷、3D赛车)", 6));

    for (set< CGaGa >::iterator it = s.begin(); it != s.end(); it++) {
        (*it).print();
    }

    return 0;
}

不加注释掉的代码，会报错：

   二进制“<”:“const _Ty”不定义该运算符或到预定义运算符可接收的类型的转换。

8、map

8.1 基础概念

 

Map 是 C++ 中非常重要的关联容器之一。它以键值对的形式存储数据，其中每个键都是唯一的，这意味着不能有重复的键。如果尝试插入一个已存在的键，将会覆盖该键对应的值。

Map 的内部结构是红黑树，这使得它具有很多优点。首先，数据是有序的，这有助于高效地进行查找、插入和删除操作。查找、插入、删除的平均和最坏时间复杂度都是 O (log n)，其中 n 是 map 中元素的个数。

在 C++ 中，pair类是一种模板类型，定义在<utility>头文件中。它将两个不同类型的值组合成一个单一的对象。对于map容器来说，map中的每个元素都是一个pair类型。map底层的红黑树节点中的数据，使用pair<Key,T>存储键值对数据。

 

#include <iostream>
#include <map>
#include <set>
using namespace std;

int main() {
    pair<int, int> p1;
    p1.first = 13;
    p1.second = 14;
    cout << p1.first << p1.second << endl;

    pair<int, string> p2(2, "333");
    cout << p2.first << p2.second << endl;

    pair<char, int> p3 = make_pair(52, 0); // '0' -> 48,   '1' -> 49 ... '4' -> 52
    cout << p3.first << p3.second << endl;

    map<int, int> m;
    set<int> s;

    return 0;
}

8.2 对象创建

#include <iostream>
#include <map>
using namespace std;

void printMap(const map<int, int>& m) {
    for (map<int, int>::const_iterator it = m.begin(); it != m.end(); it++) {
        // it->first,  it->second
        cout << "key = " << it->first << " " << " value = " << it->second << endl;
    }
    cout << "----------------------------" << endl;
}

int main() {
    // 1. 默认构造函数
    map<int, int> m1;
    cout << "m1: " << endl;
    printMap(m1);//空

    // 2. 初始化列表
    map<int, int> m2_1 = {
        pair<int, int>(1, 10),
        pair<int, int>(4, 24),
        pair<int, int>(3, 43),
        pair<int, int>(2, 15)
    };
    cout << "m2_1: " << endl;//1 2 3 4
    printMap(m2_1);

    map<int, int> m2_2({
        pair<int, int>(1, 18),
        pair<int, int>(4, 23),
        pair<int, int>(3, 41),
        pair<int, int>(2, 11)
        });
    cout << "m2_2: " << endl;
    printMap(m2_2);

    // 3. 迭代器
    map<int, int> m3(m2_1.begin(), m2_1.end());
    cout << "m3: " << endl;
    printMap(m3);

    // 4. 拷贝构造
    map<int, int> m4(m2_2);
    cout << "m4: " << endl;
    printMap(m4);

    return 0;
}

8.3 赋值操作

#include <iostream>
#include <map>
using namespace std;

void printMap(const map<int, int>& m) {
    for (map<int, int>::const_iterator it = m.begin(); it != m.end(); it++) {
        // it->first,  it->second
        cout << "key = " << it->first << " " << " value = " << it->second << endl;
    }
    cout << "----------------------------" << endl;
}

int main() {
    map<int, int> m = {
        pair<int, int>(1, 10),
        pair<int, int>(4, 24),
        pair<int, int>(3, 43),
        pair<int, int>(2, 15),
    };
    cout << "m: " << endl;
    printMap(m);

    // 1. = 对象
    map<int, int> m1;
    m1 = m;
    cout << "m1: " << endl;
    printMap(m1);

    // 2. = 初始化列表
    map<int, int> m2;
    m2 = {
        pair<int, int>(1, 8),
        pair<int, int>(4, 36),
        pair<int, int>(3, 18),
        pair<int, int>(2, 22),
    };
    cout << "m2: " << endl;
    printMap(m2);


    return 0;
}

8.4 大小操作

#include <iostream>
#include <map>
using namespace std;

int main() {
    map<int, int> m1;
    cout << "m1.empty() = " << m1.empty() << endl;//1
    cout << "m1.size()  = " << m1.size() << endl;//0

    map<int, int> m2 = { pair<int, int>(1, 10),pair<int, int>(3, 5),pair<int, int>(4, 8) };
    cout << "m2.empty() = " << m2.empty() << endl;//0
    cout << "m2.size()  = " << m2.size() << endl;//3

    return 0;
}

8.5 数据插入

#include <iostream>
#include <map>
using namespace std;

void printMap(const map<int, int>& m) {
    for (map<int, int>::const_iterator it = m.begin(); it != m.end(); it++) {
        // it->first,  it->second
        cout << "key = " << it->first << " " << " value = " << it->second << endl;
    }
    cout << "----------------------------" << endl;
}

int main() {
    map<int, int> m;

    // 1
    m.insert(pair<int, int>(1, 10));
    printMap(m);

    // 2
    m.insert(make_pair(3, 20));
    printMap(m);

    // 3
    m.insert(map<int, int>::value_type(2, 78));
    printMap(m);

    // 4
    m[4] = 6;
    printMap(m);

    // 5
    pair< map<int, int>::iterator, bool > ret = m.insert(make_pair(3, 21));//key在，插入失败
    cout << "insert(3, 21) = " << ret.second << endl;
    printMap(m);

    // 6
    m[3] = 22;
    printMap(m);//改变 20 变成 22

    // 7
    m[0];//键不存在的情况，会插入
    printMap(m);//m[0] 变为 0 0

    return 0;
}

8.6 数据查找

#include <iostream>
#include <map>
using namespace std;

void printMap(const map<int, int>& m) {
    for (map<int, int>::const_iterator it = m.begin(); it != m.end(); it++) {
        // it->first,  it->second
        cout << "key = " << it->first << " " << " value = " << it->second << endl;
    }
    cout << "----------------------------" << endl;
}

int main() {
    map<int, int> m = {
        pair<int, int>(1, 4),
        pair<int, int>(3, 20),
        pair<int, int>(2, 80),
        pair<int, int>(4, 17),
    };

    for (int i = 4; i <= 5; ++i) {
        map<int, int>::iterator it = m.find(i);
        if (it != m.end()) {
            cout << "找到键值对：（" << it->first << "," << it->second << "）" << endl;
        }
        else {
            cout << "未找到键：" << i << endl;
        }
    }


    return 0;
}

8.7 数据删除

#include <iostream>
#include <map>
using namespace std;

void printMap(const map<int, int>& m) {
    for (map<int, int>::const_iterator it = m.begin(); it != m.end(); it++) {
        // it->first,  it->second
        cout << "key = " << it->first << " " << " value = " << it->second << endl;
    }
    cout << "----------------------------" << endl;
}

int main() {
    map<int, int> m = {
        pair<int, int>(1, 4),
        pair<int, int>(3, 30),
        pair<int, int>(2, 80),
        pair<int, int>(4, 90),
    };
    printMap(m);

    m.erase(1);//删除1
    printMap(m);

    m.erase(m.begin());//删除2
    printMap(m);

    m.erase(m.begin(), m.end());
    printMap(m);

    m = {
        pair<int, int>(1, 4),
        pair<int, int>(3, 30),
        pair<int, int>(2, 80),
        pair<int, int>(4, 90),
    };
    m.clear();
    printMap(m);

    return 0;
}

8.8 数据修改

#include <iostream>
#include <map>
using namespace std;

void printMap(const map<int, int>& m) {
    for (map<int, int>::const_iterator it = m.begin(); it != m.end(); it++) {
        // it->first,  it->second
        cout << "key = " << it->first << " " << " value = " << it->second << endl;
    }
    cout << "----------------------------" << endl;
}

int main() {
    map<int, int> m;
    m.insert(make_pair(1, 20));
    m.insert(make_pair(2, 330));
    m.insert(make_pair(3, 4440));

    m[3] = 888;
    printMap(m);

    m[2]++;
    printMap(m);

    m[1] -= 21;
    printMap(m);

    return 0;
}

8.9 数据统计

#include <iostream>
#include <map>
using namespace std;

void printMap(const map<int, int>& m) {
    for (map<int, int>::const_iterator it = m.begin(); it != m.end(); it++) {
        // it->first,  it->second
        cout << "key = " << it->first << " " << " value = " << it->second << endl;
    }
    cout << "----------------------------" << endl;
}

int main() {
    map<int, int> m;
    m.insert(make_pair(1, 20));
    m.insert(make_pair(2, 330));
    m.insert(make_pair(3, 4440));

    m[3] = 888;
    printMap(m);

    m[2]++;
    printMap(m);

    m[1] -= 21;
    printMap(m);//-1

    return 0;
}

相关文章：

  • 【补充】RustDesk一键部署及账号登录配置
  • 算法-二叉树篇20-二叉搜索树中的众数
  • 探索分布式事务与Seata：构建可靠的Spring微服务架构
  • MySQL零基础教程11—拼接/计算
  • 监控视频流web端播放
  • Vue.js 组件开发全面详解及应用案例
  • 【量化金融自学笔记】--开篇.基本术语及学习路径建议
  • Hive配置
  • 计算机毕业设计SpringBoot+Vue.js人口老龄化社区服务与管理平台 (源码+文档+PPT+讲解)
  • PHP实现登录和注册（附源码）
  • 如何通过rust实现自己的web登录图片验证码
  • react 中，使用antd layout布局中的sider 做sider的展开和收起功能
  • 对于运维稳定性建设的一些思考
  • Let‘s Encrypt 获取免费SSL证书
  • 如何在 IntelliJ IDEA 中集成 DeepSeek
  • DeepSeek实操教程（清华、北大）
  • MATLAB环境下从信号中去除60Hz工频干扰噪声
  • git push失败
  • 微服务笔记 2025/2/15
  • 计算机网络实验2-虚拟局域网（VLAN）划分
  • wordpress 密码重置/常用seo站长工具
  • 做搜索网站能发财吗/网络营销策划总结
  • asp网站如何安装/欧洲站fba
  • 哈尔滨高端品牌网站建设/百度推广客服电话24小时
  • 北京市建委网站官网/凡科建站客服电话
  • 用vue.js做网站的好处/网站排名优化化快排优化