遍历容器。
transform(iterator beg1, iterator end1, iterator beg2, _func)搬运容器，目标容器需要提前开辟空间。
#include查找算法 find(iterator beg, iterator end, value);#include #include using namespace std; class Print { public: void operator()(int val) { cout << val << " "; } }; void test01() { vector vec = { 0,1,2,3,4,5,6,7,8,9 }; for_each(vec.begin(), vec.end(), Print()); cout << endl; } class Transform { public: int operator()(int val) { return val; } }; void test02() { vector vec = { 0,1,2,3,4,5,6,7,8,9 }; // 目标容器 vector vTarget; // 目标容器需要提前开辟空间 vTarget.resize(vec.size()); transform(vec.begin(), vec.end(), vTarget.begin(), Transform()); for_each(vTarget.begin(), vTarget.end(), Print()); } int main() { test01(); test02(); system("pause"); return 0; }
按值查找元素，找到返回指定位置的迭代器，找不到返回尾后迭代器。 查找自定义数据类型时，确保该类型定义了==运算符。
#includefind_if(iterator beg, iterator end, _Pred);#include #include #include using namespace std; // 查找内置数据类型 void test01() { vector vec = { 0,1,2,3,4,5,6,7,8,9 }; // 查找容器中是否有5这个元素 vector ::iterator it = find(vec.begin(), vec.end(), 5); if (it == vec.end()) { cout << "没有找到!" << endl; } else { cout << "找到!" << endl; } } // 查找自定义数据类型 class Person { public: Person(string name, int age) { this->m_Name = name; this->m_Age = age; } // ==运算符 bool operator==(const Person& p) { if (this->m_Name == p.m_Name && this->m_Age == p.m_Age) { return true; } return false; } public: string m_Name; int m_Age; }; void test02() { vector vec; vec.emplace_back("aaa", 10); vec.emplace_back("bbb", 20); vec.emplace_back("ccc", 30); vec.emplace_back("ddd", 40); vector ::iterator it = find(vec.begin(), vec.end(), Person("aaa", 10)); if (it == vec.end()) { cout << "没有找到!" << endl; } else { cout << "找到!" << endl; } } int main() { test01(); test02(); system("pause"); return 0; }
按值查找元素，找到返回指定位置的迭代器，找不到返回尾后迭代器。
#includeadjacent_find(iterator beg, iterator end);#include #include #include using namespace std; // 查找内置数据类型 class GreaterFive { public: bool operator()(int val) { return val > 5; } }; void test01() { vector vec = { 0,1,2,3,4,5,6,7,8,9 }; vector ::iterator it = find_if(vec.begin(), vec.end(), GreaterFive()); if (it == vec.end()) { cout << "没有找到!" << endl; } else { cout << "找到!" << endl; } } // 查找自定义数据类型 class Person { public: Person(string name, int age) { this->m_Name = name; this->m_Age = age; } public: string m_Name; int m_Age; }; class Greater20 { public: bool operator()(Person& p) { return p.m_Age > 20; } }; void test02() { vector vec; // 创建数据 vec.emplace_back("aaa", 10); vec.emplace_back("bbb", 20); vec.emplace_back("ccc", 30); vec.emplace_back("ddd", 40); // 查找年龄大于20的人 vector ::iterator it = find_if(vec.begin(), vec.end(), Greater20()); if (it == vec.end()) { cout << "没有找到!" << endl; } else { cout << "找到!" << endl; } } int main() { test01(); test02(); system("pause"); return 0; }
查找相邻重复元素，返回相邻元素的第一个位置的迭代器，找不到返回尾后迭代器。
bool binary_search(iterator beg, iterator end, value);利用二分查找法查找指定的元素，在无序序列中不可用！
#includecount(iterator beg, iterator end, value);#include #include #include using namespace std; void test01() { vector vec = { 1,2,5,2,4,4,3 }; // 查找相邻重复元素 vector ::iterator it = adjacent_find(vec.begin(), vec.end()); if (it == vec.end()) { cout << "找不到!" << endl; } else { cout << "找到!" << endl; } sort(vec.begin(), vec.end()); // 查找有序容器中是否有元素2 bool ret = binary_search(vec.begin(), vec.end(), 2); if (ret) { cout << "找到!" << endl; } else { cout << "未找到!" << endl; } } int main() { test01(); system("pause"); return 0; }
统计元素出现次数。
#includecount_if(iterator beg, iterator end, _Pred);#include #include #include using namespace std; // 统计内置数据类型 void test01() { vector v = { 1,2,4,5,3,4,4 }; int num = count(v.begin(), v.end(), 4); cout << "4的个数为： " << num << endl; } // 统计自定义数据类型 class Person { public: Person(string name, int age) { this->m_Name = name; this->m_Age = age; } // ==运算符 bool operator==(const Person& p) { if (this->m_Age == p.m_Age) { return true; } return false; } public: string m_Name; int m_Age; }; void test02() { vector v; v.emplace_back("刘备", 35); v.emplace_back("关羽", 35); v.emplace_back("张飞", 35); v.emplace_back("赵云", 30); v.emplace_back("曹操", 25); Person p("诸葛亮", 35); int num = count(v.begin(), v.end(), p); cout << "num = " << num << endl; } int main() { test01(); test02(); system("pause"); return 0; }
按条件统计元素出现次数。
#include常用排序算法 sort(iterator beg, iterator end, _Pred);#include #include using namespace std; class Greater4 { public: bool operator()(int val) { return val >= 4; } }; // 统计内置数据类型 void test01() { vector vec = { 1,2,4,5,3,4,4 }; int num = count_if(vec.begin(), vec.end(), Greater4()); } // 统计自定义数据类型 class Person { public: Person(string name, int age) { this->m_Name = name; this->m_Age = age; } public: string m_Name; int m_Age; }; class AgeLess35 { public: bool operator()(const Person& p) { return p.m_Age < 35; } }; void test02() { vector vec; vec.emplace_back("刘备", 35); vec.emplace_back("关羽", 35); vec.emplace_back("张飞", 35); vec.emplace_back("赵云", 30); vec.emplace_back("曹操", 25); int num = count_if(vec.begin(), vec.end(), AgeLess35()); } int main() { test01(); test02(); system("pause"); return 0; }
对容器内元素进行排序，默认按升序排序。
#includerandom_shuffle(iterator beg, iterator end);#include #include using namespace std; void test01() { vector vec = { 10,30,50,20,40 }; // 默认升序排序 sort(vec.begin(), vec.end()); for (auto v : vec) cout << v << " "; cout << endl; // 10 20 30 40 50 // 设置降序排序 sort(vec.begin(), vec.end(), greater ()); for (auto v : vec) cout << v << " "; cout << endl; // 50 40 30 20 10 } int main() { test01(); system("pause"); return 0; }
指定范围内的元素随机调整次序。
#includemerge(iterator beg1, iterator end1, iterator beg2, iterator end2, iterator dest);#include #include #include using namespace std; void test01() { // 随机数种子 srand((unsigned int)time(NULL)); vector vec = { 0,1,2,3,4,5,6,7,8,9 }; for_each(vec.begin(), vec.end(), [](int val) {cout << val << " "; }); cout << endl; // 0 1 2 3 4 5 6 7 8 9 // 利用洗牌算法 打乱顺序 random_shuffle(vec.begin(), vec.end()); for_each(vec.begin(), vec.end(), [](int val) {cout << val << " "; }); cout << endl; // 7 6 5 2 3 9 8 4 1 0 } int main() { test01(); system("pause"); return 0; }
两个容器元素合并，并存储到另一容器中，目标容器需要提前开辟空间，两个容器必须是有序的！
#includereverse(iterator beg, iterator end);#include #include using namespace std; void test01() { vector vec1 = { 0,1,2,3,4,5,6,7,8,9 }; vector vec2 = { 1,2,3,4,5,6,7,8,9,10 }; // 目标容器 vector vtarget; // 目标容器需要提前开辟空间 vtarget.resize(vec1.size() + vec2.size()); // 合并两个有序序列 merge(vec1.begin(), vec1.end(), vec2.begin(), vec2.end(), vtarget.begin()); for (auto v : vtarget) cout << v << " "; cout << endl; // 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 } int main() { test01(); system("pause"); return 0; }
将容器内元素进行反转。
#include常用拷贝和替换算法 copy(iterator beg, iterator end, iterator dest);#include #include using namespace std; void test01() { vector vec = { 1,2,3,4,5,6,7,8,9 }; cout << "反转前： " << endl; for (auto v : vec) cout << v << " "; cout << endl; // 1 2 3 4 5 6 7 8 9 reverse(vec.begin(), vec.end()); cout << "反转后： " << endl; for (auto v : vec) cout << v << " "; cout << endl; // 9 8 7 6 5 4 3 2 1 } int main() { test01(); system("pause"); return 0; }
容器内指定范围的元素拷贝到另一容器中，目标容器需要提前开辟空间。
#includereplace(iterator beg, iterator end, oldvalue, newvalue);#include #include using namespace std; void test01() { vector vec1 = { 0,1,2,3,4,5,6,7,8,9 }; vector vec2; // 目标容器提前开辟空间 vec2.resize(vec1.size()); copy(vec1.begin(), vec1.end(), vec2.begin()); for (auto v : vec2) cout << v << " "; cout << endl; // 0 1 2 3 4 5 6 7 8 9 } int main() { test01(); system("pause"); return 0; }
将容器内指定范围的旧元素修改为新元素。
#includereplace_if(iterator beg, iterator end, _pred, newvalue);#include #include using namespace std; void test01() { vector vec = { 20,30,20,40,50,10,20 }; cout << "替换前：" << endl; for (auto v : vec) cout << v << " "; cout << endl; // 20 30 20 40 50 10 20 // 20 -> 666 cout << "替换后：" << endl; replace(vec.begin(), vec.end(), 20, 2000); for (auto v : vec) cout << v << " "; cout << endl; // 666 30 666 40 50 10 666 } int main() { test01(); system("pause"); return 0; }
将区间内满足条件的元素，替换成指定元素。
#includeswap(container c1, container c2);#include #include using namespace std; class ReplaceGreater30 { public: bool operator()(int val) { return val >= 30; } }; void test01() { vector vec = { 20,30,20,40,50,10,20 }; cout << "替换前：" << endl; for (auto v : vec) cout << v << " "; cout << endl; // 20 30 20 40 50 10 20 // ≥30 -> 666 cout << "替换后：" << endl; replace_if(vec.begin(), vec.end(), ReplaceGreater30(), 3000); for (auto v : vec) cout << v << " "; cout << endl; // 20 666 20 666 666 10 20 } int main() { test01(); system("pause"); return 0; }
互换两个容器的元素，交换的容器要同种类型。
#include常用算术生成算法#include #include using namespace std; void test01() { vector vec1 = { 0,1,2,3,4,5 }; vector vec2 = { 6,7,8,9,10,11 }; cout << "交换前： " << endl; for (auto v : vec1) cout << v << " "; cout << endl; // 0 1 2 3 4 5 for (auto v : vec2) cout << v << " "; cout << endl; // 6 7 8 9 10 11 cout << "交换后： " << endl; swap(vec1, vec2); for (auto v : vec1) cout << v << " "; cout << endl; // 6 7 8 9 10 11 for (auto v : vec2) cout << v << " "; cout << endl; // 0 1 2 3 4 5 } int main() { test01(); system("pause"); return 0; }
算术生成算法属于小型算法，使用时包含的头文件为 #include
计算区间内容器元素累计总和。
fill(iterator beg, iterator end, value);向容器中填充元素。
#include常用集合算法 set_intersection(iterator beg1, iterator end1, iterator beg2, iterator end2, iterator dest);#include #include using namespace std; void test01() { vector vec; vec.reserve(101); for (int i = 0; i <= 100; i++) { vec.push_back(i); } int total = accumulate(vec.begin(), vec.end(), 0); cout << "total = " << total << endl; // 5050 } void test02() { vector vec; vec.resize(5); // 填充vector有数据的部分 size fill(vec.begin(), vec.end(), 100); for (auto v : vec) cout << v << " "; cout << endl; // 100 100 100 100 100 } int main() { test01(); test02(); system("pause"); return 0; }
求两个容器的交集。
- 求交集的两个集合必须是有序序列
- 目标容器开辟空间为两个容器容量中的较小值
- set_intersection返回交集中最后一个元素的下一个位置
求两个集合的并集。
- 求并集的两个集合必须的有序序列
- 目标容器开辟空间为两个容器容量之和
- set_intersection返回并集中最后一个元素的下一个位置
求两个容器的差集。
- 求差集的两个集合必须是有序序列
- 目标容器开辟空间为两个容器容量中的较大值
- set_difference返回差集中最后一个元素的下一个位置
#include#include #include using namespace std; void test01() { vector vec1 = { 1,2,3,100,200,300 }; vector vec2 = { 4,5,6,100,200,300 }; vector vTarget; // 目标容器开辟空间为两个容器容量中的较小值 vTarget.resize(min(vec1.size(), vec2.size())); // 返回目标容器结果的“尾后迭代器” vector ::iterator itEnd = set_intersection(vec1.begin(), vec1.end(), vec2.begin(), vec2.end(), vTarget.begin()); for (auto it = vTarget.begin(); it != itEnd; ++it) cout << *it << " "; cout << endl; // 100 200 300 for (auto v : vTarget) cout << v << " "; cout << endl; // 100 200 300 0 0 0 } void test02() { vector vec1 = { 1,2,3,100,200,300 }; vector vec2 = { 4,5,6,100,200,300 }; vector vTarget; // 目标容器开辟空间为两个容器容量之和 vTarget.resize(vec1.size() + vec2.size()); // 返回目标容器结果的“尾后迭代器” vector ::iterator itEnd = set_union(vec1.begin(), vec1.end(), vec2.begin(), vec2.end(), vTarget.begin()); for (auto it = vTarget.begin(); it != itEnd; ++it) cout << *it << " "; cout << endl; // 1 2 3 4 5 6 100 200 300 for (auto v : vTarget) cout << v << " "; cout << endl; //1 2 3 4 5 6 100 200 300 0 0 0 } void test03() { vector vec1 = { 1,2,3,100,200,300 }; vector vec2 = { 4,5,6,100,200,300 }; vector vTarget; // 目标容器开辟空间为两个容器容量中的较大值 vTarget.resize(max(vec1.size(), vec2.size())); cout << "v1与v2的差集为： " << endl; vector ::iterator itEnd = set_difference(vec1.begin(), vec1.end(), vec2.begin(), vec2.end(), vTarget.begin()); for (auto it = vTarget.begin(); it != itEnd; ++it) cout << *it << " "; cout << endl; // 1 2 3 cout << "v2与v1的差集为： " << endl; itEnd = set_difference(vec2.begin(), vec2.end(), vec1.begin(), vec1.end(), vTarget.begin()); for (auto it = vTarget.begin(); it != itEnd; ++it) cout << *it << " "; cout << endl; // 4 5 6 } int main() { test01(); test02(); test03(); system("pause"); return 0; }
参考：https://www.bilibili.com/video/BV1et411b73Z
