STL中给出的算法，大部分定义在头文件algorithm里头，还有一些定义在numeric头文件里头，有时候为了绑定适配器还需要引入头文件functional。STL算法通常配合容器使用，它们之间通过迭代器建立联系。
一、常用的遍历算法
(1)for_each
1 #include <iostream> 2 #include <vector> 3 #include <string> 4 #include <algorithm> 5 #include <functional> 6 using namespace std; 7 8 //普通函数 9 void PrintTest01(const int &val) 10 { 11 cout << val << " "; 12 } 13 14 //函数对象 15 class PrintTest01Pro 16 { 17 public: 18 void operator()(int &val) const 19 { 20 cout << val << " "; 21 } 22 }; 23 24 void test01(void) 25 { 26 vector<int> v; 27 for (int i = 0; i < 6; ++i) 28 v.push_back(i+1); 29 30 //给for_each传入普通函数PrintTest01 31 for_each(v.begin(), v.end(), PrintTest01); 32 33 cout << endl << "--------------" << endl; 34 35 //给for_each传入函数对象 36 for_each(v.begin(), v.end(), PrintTest01Pro()); 37 } 38 39 //函数对象 40 class PrintTest02 41 { 42 public: 43 PrintTest02() 44 { 45 mCount = 0; 46 } 47 void operator()(const int &val) 48 { 49 mCount++; 50 cout << val << " "; 51 } 52 public: 53 int mCount; 54 }; 55 56 //for_each返回值：函数对象 57 void test02(void) 58 { 59 vector<int> v; 60 for (int i = 0; i < 6; ++i) 61 v.push_back(i + 1); 62 63 //给for_each传入普通函数 64 PrintTest02 ret = for_each(v.begin(), v.end(), PrintTest02()); 65 cout << endl << "调用次数:" << ret.mCount << endl; 66 } 67 68 69 class PrintTest03 : public binary_function<int,string,void> 70 { 71 public: 72 void operator()(int val, string str) const 73 { 74 cout << str << " " << val << endl; 75 } 76 }; 77 78 //for_each绑定参数输出 79 void test03(void) 80 { 81 vector<int> v; 82 for (int i = 0; i < 6; ++i) 83 v.push_back(i + 1); 84 85 for_each(v.begin(), v.end(), bind2nd(PrintTest03(),string("我是for_each的参数"))); 86 } 87 88 int main(void) 89 { 90 //test01(); 91 //test02(); 92 //test03(); 93 return 0; 94 }
(2)transform
1 #include<iostream> 2 #include<vector> 3 #include<string> 4 #include<algorithm> 5 #include<functional> 6 using namespace std; 7 8 class TransformTest01 9 { 10 public: 11 int operator()(int val) 12 { 13 //让val加上增量100，但是增量被写死了，不灵活 14 return val + 100; 15 } 16 }; 17 18 void test01(void) 19 { 20 //vector的元素类型为基本类型 21 vector<int> v1; 22 v1.push_back(1); 23 v1.push_back(2); 24 v1.push_back(3); 25 26 /* transform不会给目标容器分配内存，所以需要提前分配好内存 27 分配内存可以使用resize()，不能使用reserve() */ 28 vector<int> v2(v1.size()); 29 30 //将v1容器中的元素搬运到v2容器中 31 transform(v1.begin(), v1.end(), v2.begin(), TransformTest01()); 32 33 //输出vector 34 for_each(v2.begin(), v2.end(), [](int val)->void{ cout << val << " "; }); 35 cout << endl; 36 } 37 38 class TransformTest02 : public binary_function<int, int, int> 39 { 40 public: 41 int operator()(int val,int addNum) const 42 { 43 //让val加上增量addNum 44 return val + addNum; 45 } 46 }; 47 48 void test02(void) 49 { 50 //vector的元素类型为基本类型 51 vector<int> v1; 52 v1.push_back(1); 53 v1.push_back(2); 54 v1.push_back(3); 55 56 vector<int> v2(v1.size()); 57 58 /* 将v1容器中的元素搬运到v2容器中，搬运过程中让每个 59 元素加一个指定值,需要绑定适配器 */ 60 transform(v1.begin(), v1.end(), v2.begin(), bind2nd(TransformTest02(),100)); 61 62 //输出vector 63 for_each(v2.begin(), v2.end(), [](int val)->void{ cout << val << " "; }); 64 cout << endl; 65 } 66 67 class Person 68 { 69 public: 70 Person() 71 { 72 mName = "Undefined"; 73 mAge = 0; 74 } 75 Person(string name, int age) 76 { 77 mName = name; 78 mAge = age; 79 } 80 public: 81 string mName; 82 int mAge; 83 }; 84 85 class TransformTest03 : public binary_function<Person,int,Person> 86 { 87 public: 88 Person operator()(Person person, int addAge) const 89 { 90 return Person(person.mName, person.mAge + addAge); 91 } 92 }; 93 94 void test03() 95 { 96 //vector的元素类型为自定义类型 97 vector<Person> v1; 98 v1.push_back(Person("John", 10)); 99 v1.push_back(Person("Peter", 20)); 100 v1.push_back(Person("Marry", 30)); 101 v1.push_back(Person("John", 40)); 102 103 vector<Person> v2(v1.size()); 104 105 transform(v1.begin(), v1.end(), v2.begin(), bind2nd(TransformTest03(),20)); 106 107 for (vector<Person>::iterator it = v2.begin(); it != v2.end(); ++it) 108 { 109 cout << "Name:" << it->mName << " Age:" << it->mAge << endl; 110 } 111 } 112 113 class TransformTest04 : public binary_function<Person*, int, Person*> 114 { 115 public: 116 Person *operator()(Person *person, int addAge) const 117 { 118 return new Person(person->mName, person->mAge + addAge); 119 } 120 }; 121 122 void test04() 123 { 124 //vector容器元素为自定义类型的指针类型 125 vector<Person*> v1; 126 v1.push_back(new Person("John", 10)); 127 v1.push_back(new Person("Peter", 20)); 128 v1.push_back(new Person("Marry", 30)); 129 v1.push_back(new Person("John", 40)); 130 131 vector<Person*> v2(v1.size()); 132 133 transform(v1.begin(), v1.end(), v2.begin(), bind2nd(TransformTest04(), 30)); 134 135 for (vector<Person*>::iterator it = v2.begin(); it != v2.end(); ++it) 136 { 137 cout << "Name:" << (*it)->mName << " Age:" << (*it)->mAge << endl; 138 } 139 } 140 141 int main(void) 142 { 143 //test01(); 144 //test02(); 145 //test03(); 146 //test04(); 147 return 0; 148 }
二、常用查找算法
(1)find/find_if
1 #include <iostream> 2 #include <vector> 3 #include <string> 4 #include <algorithm> 5 #include <functional> 6 using namespace std; 7 8 //查找基础数据类型 9 void test01(void) 10 { 11 vector<int> v; 12 v.push_back(10); 13 v.push_back(20); 14 v.push_back(30); 15 v.push_back(40); 16 /* 17 find返回值: 18 1、查找成功，返回指向这个值的迭代器 19 2、查找失败，返回指向end()的迭代器 20 */ 21 vector<int>::iterator it = find(v.begin(), v.end(), 40); 22 if (it != v.end()) 23 cout << "找到了 " << *it << endl; 24 else 25 cout << "没找到" << endl; 26 } 27 28 class Person 29 { 30 public: 31 Person() 32 { 33 mName = "Undefined"; 34 mAge = 0; 35 } 36 Person(string name,int age) 37 { 38 mName = name; 39 mAge = age; 40 } 41 bool operator==(const Person &p) 42 { 43 return mName == p.mName && mAge == p.mAge; 44 } 45 public: 46 string mName; 47 int mAge; 48 }; 49 50 //查找自定义类型对象：需要重载==操作符 51 void test02(void) 52 { 53 vector<Person> v; 54 v.push_back(Person("John", 10)); 55 v.push_back(Person("Peter", 20)); 56 v.push_back(Person("Snow", 30)); 57 v.push_back(Person("Marry", 40)); 58 59 vector<Person>::iterator it = find(v.begin(), v.end(), Person("Marry", 40)); 60 if (it != v.end()) 61 cout << "找到了! Name:" << it->mName << " Age:" << it->mAge << endl; 62 else 63 cout << "没找到" << endl; 64 } 65 66 class search_condition : public binary_function<Person*, Person*, bool> 67 { 68 public: 69 bool operator()(Person *p1, Person *p2)const 70 { 71 return p1->mName == p2->mName && p1->mAge == p2->mAge; 72 } 73 }; 74 75 // find_if 查找指针对象 76 void test03(void) 77 { 78 vector<Person*> v; 79 Person p1("John", 10); 80 Person p2("Peter", 20); 81 Person p3("Snow", 30); 82 Person p4("Marry", 40); 83 v.push_back(&p1); 84 v.push_back(&p2); 85 v.push_back(&p3); 86 v.push_back(&p4); 87 88 //find_if函数根据用户提供的search_considtion()和&p2去查找 89 vector<Person*>::iterator it = find_if(v.begin(), v.end(), bind2nd(search_condition(), &p2)); 90 91 if (it != v.end()) 92 cout << "找到了! Name:" << (*it)->mName << " Age:" << (*it)->mAge << endl; 93 else 94 cout << "没找到" << endl; 95 } 96 97 int main(void) 98 { 99 //test01(); 100 //test02(); 101 //test03(); 102 return 0; 103 }
(2)adjacent_find
1 #include <iostream> 2 #include <vector> 3 #include <algorithm> 4 using namespace std; 5 6 //adjacent_find 查找相邻重复元素; 7 void test01() 8 { 9 vector<int> v; 10 v.push_back(10); 11 v.push_back(20); 12 v.push_back(30); 13 v.push_back(30); 14 15 vector<int>::iterator it = adjacent_find(v.begin(),v.end()); 16 if (it == v.end()) 17 cout << "没找到" << endl; 18 else 19 cout << "找到了,相邻重复的元素：" << *it << endl; 20 } 21 22 23 int main(void) 24 { 25 //test01(); 26 return 0; 27 }
(3)binary_search
1 #include <iostream> 2 #include <vector> 3 #include <string> 4 #include <algorithm> 5 #include <functional> 6 using namespace std; 7 8 //binary_search二分查找法 需要序列有序的，找到了返回值true，未找到返回false 9 void test01(void) 10 { 11 vector<int> v; 12 for (int i = 1; i <= 10; ++i) 13 v.push_back(i*i); 14 if (true == binary_search(v.begin(), v.end(), 64)) 15 cout << "找到了" << endl; 16 else 17 cout << "未找到" << endl; 18 19 } 20 21 class Person 22 { 23 public: 24 Person() 25 { 26 mName = "Undefined"; 27 mAge = 0; 28 } 29 Person(string name, int age) 30 { 31 mName = name; 32 mAge = age; 33 } 34 bool operator<(const Person &p) const 35 { 36 if (mName == p.mName) 37 { 38 return mAge < p.mAge; 39 } 40 return mName < p.mName; 41 } 42 public: 43 string mName; 44 int mAge; 45 }; 46 47 //二分查找自定义类型对象：需要重载<操作符,重载函数为const函数 48 void test02(void) 49 { 50 vector<Person> v; 51 v.push_back(Person("John", 10)); 52 v.push_back(Person("Peter", 20)); 53 v.push_back(Person("Snow", 30)); 54 v.push_back(Person("Marry", 40)); 55 56 if (true == binary_search(v.begin(), v.end(), Person("Peter", 20))) 57 cout << "找到了"<< endl; 58 else 59 cout << "没找到" << endl; 60 } 61 62 int main(void) 63 { 64 //test01(); 65 //test02(); 66 return 0; 67 }
(4)count/count_if
1 #include <iostream> 2 #include <vector> 3 #include <algorithm> 4 #include <functional> 5 using namespace std; 6 7 class GreaterThanTwo 8 { 9 public: 10 bool operator()(int v) 11 { 12 return v > 10; 13 } 14 }; 15 16 class GreaterThanNumPro : public binary_function<int, int, bool> 17 { 18 public: 19 bool operator()(int v,int num) const 20 { 21 return v > num; 22 } 23 }; 24 25 //count count_if 统计元素的个数 26 void test01(void) 27 { 28 vector<int> v; 29 v.push_back(10); 30 v.push_back(10); 31 v.push_back(20); 32 v.push_back(21); 33 v.push_back(22); 34 v.push_back(10); 35 36 //统计元素中为10的元素个数 37 int num = count(v.begin(), v.end(), 10); 38 cout << "10的个数为" << num << endl; 39 40 //统计大于10的元素个数 41 num = count_if(v.begin(), v.end(), GreaterThanTwo()); 42 cout << "大于10的元素个数为" << num << endl; 43 44 //统计大于number的元素个数 45 int number = 20; 46 num = count_if(v.begin(), v.end(), bind2nd(GreaterThanNumPro(), number)); 47 cout << "大于10的元素个数为" << num << endl; 48 } 49 50 int main(void) 51 { 52 //test01(); 53 return 0; 54 }
三、常用排序算法
(1)merge
1 #include <iostream> 2 #include <vector> 3 #include <algorithm> 4 #include <functional> 5 using namespace std; 6 7 //merge 合并两个有序序序列,默认从小到大排序 8 void test01() 9 { 10 vector<int> v1; 11 vector<int> v2; 12 for (int i = 1; i <= 5; ++i) 13 { 14 v1.push_back(i); 15 v2.push_back(i + 2); 16 } 17 vector<int> vTarget(v1.size()+v2.size()); 18 19 merge(v1.begin(), v1.end(), v2.begin(), v2.end(), vTarget.begin()); 20 21 //输出vTarget 22 for_each(vTarget.begin(), vTarget.end(), [](int val)->void{cout << val << " "; } ); 23 24 } 25 26 class MyCompare 27 { 28 public: 29 bool operator()(int v1, int v2) 30 { 31 return v1 > v2; 32 } 33 }; 34 35 //merge 改变默认排序规则，按照从大到小排序 36 void test02() 37 { 38 vector<int> v1; 39 vector<int> v2; 40 for (int i = 5; i > 0; --i) 41 { 42 v1.push_back(i); 43 v2.push_back(i+3); 44 } 45 vector<int> vTarget(v1.size() + v2.size()); 46 47 merge(v1.begin(), v1.end(), v2.begin(), v2.end(), vTarget.begin(), MyCompare()); 48 49 //输出vTarget 50 for_each(vTarget.begin(), vTarget.end(), [](int val)->void{cout << val << " "; }); 51 } 52 53 int main(void) 54 { 55 //test01(); 56 //test02(); 57 return 0; 58 }
(2)sort
1 //sort算法：使用sort算法，容器必须支持随机访问。list不能用sort算法 2 #include <iostream> 3 #include <vector> 4 #include <algorithm> 5 #include <functional> 6 using namespace std; 7 8 void test01(void) 9 { 10 vector<int> v; 11 v.push_back(10); 12 v.push_back(70); 13 v.push_back(50); 14 v.push_back(20); 15 16 //sort默认按照从小到大排序 17 sort(v.begin(), v.end()); 18 for_each(v.begin(), v.end(), [](int val)->void{cout << val << " "; }); 19 cout << endl; 20 sort(v.begin(), v.end(),greater<int>()); 21 for_each(v.begin(), v.end(), [](int val)->void{cout << val << " "; }); 22 cout << endl; 23 } 24 25 int main(void) 26 { 27 //test01(); 28 return 0; 29 }
(3)random_shuffle
1 #include <iostream> 2 #include <vector> 3 #include <algorithm> 4 #include <functional> 5 using namespace std; 6 7 //random_shuffle 洗牌，打乱容器中元素的次序 8 void test01() 9 { 10 vector<int> v; 11 v.push_back(11); 12 v.push_back(76); 13 v.push_back(13); 14 v.push_back(89); 15 v.push_back(52); 16 v.push_back(48); 17 18 for_each(v.begin(), v.end(), [](int val){cout << val << " "; }); cout << endl; 19 random_shuffle(v.begin(), v.end()); 20 for_each(v.begin(), v.end(), [](int val){cout << val << " "; }); cout << endl; 21 } 22 23 int main(void) 24 { 25 //test01(); 26 return 0; 27 }
(4)reverse
1 #include <iostream> 2 #include <vector> 3 #include <algorithm> 4 #include <functional> 5 using namespace std; 6 7 void test01() 8 { 9 vector<int> v; 10 v.push_back(1); 11 v.push_back(2); 12 v.push_back(3); 13 v.push_back(4); 14 v.push_back(5); 15 v.push_back(6); 16 17 for_each(v.begin(), v.end(), [](int val){cout << val << " "; }); cout << endl; 18 reverse(v.begin(), v.end()); 19 for_each(v.begin(), v.end(), [](int val){cout << val << " "; }); cout << endl; 20 } 21 22 int main(void) 23 { 24 test01(); 25 return 0; 26 }
四、常用拷贝和替换算法
(1)copy/copy_if
1 #include<iostream> 2 #include<vector> 3 #include<functional> 4 #include<algorithm> 5 #include<iterator> 6 using namespace std; 7 8 //copy 9 void test01(void) 10 { 11 vector<int> v1; 12 for (int i = 0; i < 10; i++){ 13 v1.push_back(i + 1); 14 } 15 vector<int> v2; 16 v2.resize(v1.size()); 17 copy(v1.begin(), v1.end(), v2.begin()); 18 copy(v2.begin(), v2.end(), ostream_iterator<int>(cout, " ")); 19 } 20 21 class CopyCondition : public binary_function<int, int , bool> 22 { 23 public: 24 bool operator()(int v1, int num) const 25 { 26 return v1 == num; 27 } 28 }; 29 30 //copy_if：按照用户传入的函数对象来拷贝 31 void test02() 32 { 33 vector<int> v1; 34 for (int i = 0; i < 10; i++){ 35 v1.push_back(i + 1); 36 } 37 vector<int> v2; 38 v2.resize(v1.size()); 39 int num = 3; 40 copy_if(v1.begin(), v1.end(), v2.begin(), bind2nd(CopyCondition(),num)); 41 copy(v2.begin(), v2.end(), ostream_iterator<int>(cout, " ")); 42 } 43 44 int main(void) 45 { 46 //test02(); 47 return 0; 48 }
(2)replace/replace_if
1 #include<iostream> 2 #include<vector> 3 #include<functional> 4 #include<algorithm> 5 #include<iterator> 6 using namespace std; 7 8 //replace 9 void test01() 10 { 11 vector<int> v; 12 v.push_back(2); 13 v.push_back(7); 14 v.push_back(2); 15 v.push_back(9); 16 v.push_back(10); 17 v.push_back(3); 18 v.push_back(0); 19 20 replace(v.begin(),v.end(),10,1000); 21 22 //输出vector 23 copy(v.begin(), v.end(), ostream_iterator<int>(cout, " ")); 24 } 25 26 27 bool ReplaceCondition(int v){ 28 return v > 2; 29 } 30 31 //replace_if：按照用户提供的函数指针来进行替换 32 void test02(void) 33 { 34 vector<int> v1; 35 v1.push_back(2); 36 v1.push_back(7); 37 v1.push_back(2); 38 v1.push_back(9); 39 v1.push_back(10); 40 v1.push_back(3); 41 v1.push_back(0); 42 43 replace_if(v1.begin(), v1.end(), ReplaceCondition, 100); 44 45 //输出替换后的vector 46 copy(v1.begin(), v1.end(), ostream_iterator<int>(cout, " ")); 47 } 48 49 int main(void) 50 { 51 //test01(); 52 //test02(); 53 return 0; 54 }
(3)swap
1 #include<iostream> 2 #include<vector> 3 #include<functional> 4 #include<algorithm> 5 #include<iterator> 6 using namespace std; 7 8 void test01() 9 { 10 vector<int> v1; 11 vector<int> v2; 12 for (int i = 0; i < 10; i++){ 13 v1.push_back(i + 1); 14 v2.push_back(i); 15 } 16 17 for_each(v1.begin(), v1.end(), [](int val){cout << val << " "; }); cout << endl; 18 for_each(v2.begin(), v2.end(), [](int val){cout << val << " "; }); cout << endl; 19 swap(v1, v2); 20 cout << "------------" << endl; 21 for_each(v1.begin(), v1.end(), [](int val){cout << val << " "; }); cout << endl; 22 for_each(v2.begin(), v2.end(), [](int val){cout << val << " "; }); cout << endl; 23 } 24 25 int main(void) 26 { 27 test01(); 28 return 0; 29 }
五、常用的算数生成算法
(1)accumulate
1 #include <iostream> 2 #include <vector> 3 #include <numeric> /* accumulate() */ 4 using namespace std; 5 6 void test01() 7 { 8 vector<int> v; 9 for (int i = 0; i <= 100; i++){ 10 v.push_back(i); 11 } 12 13 int total = accumulate(v.begin(), v.end(), 0); 14 cout << "total:" << total << endl; 15 } 16 17 int main(void) 18 { 19 test01(); 20 return 0; 21 }
(2)fill
1 #include <iostream> 2 #include <vector> 3 #include <functional> 4 #include <algorithm> 5 #include <iterator> 6 #include <numeric> /* accumulate() */ 7 using namespace std; 8 9 void test01() 10 { 11 vector<int> v; 12 v.resize(10); 13 fill(v.begin(), v.end(), 100); 14 copy(v.begin(), v.end(), ostream_iterator<int>(cout, " ")); 15 } 16 17 int main(void) 18 { 19 test01(); 20 return 0; 21 }
六、常用集合算法
(1)set_intersection/set_union/set_difference
1 #include<iostream> 2 #include<vector> 3 #include<functional> 4 #include<iterator> 5 #include<algorithm> 6 using namespace std; 7 8 //求交集 set_intersection 9 void test01(void) 10 { 11 vector<int> v1; 12 vector<int> v2; 13 for (int i = 0; i < 10; ++i) 14 v1.push_back(i); 15 for (int i = 5; i < 15; ++i) 16 v2.push_back(i); 17 vector<int> v3(v1.size() + v2.size()); 18 vector<int>::iterator MyEnd = set_intersection(v1.begin(), v1.end(), v2.begin(), v2.end(), v3.begin()); 19 copy(v3.begin(), MyEnd, ostream_iterator<int>(cout, " ")); 20 } 21 22 //求并集 set_union 23 void test02() 24 { 25 vector<int> v1; 26 vector<int> v2; 27 for (int i = 0; i < 10; ++i) 28 v1.push_back(i); 29 for (int i = 5; i < 15; ++i) 30 v2.push_back(i); 31 vector<int> v3(v1.size() + v2.size()); 32 vector<int>::iterator MyEnd = set_union(v1.begin(), v1.end(), v2.begin(), v2.end(), v3.begin()); 33 copy(v3.begin(), MyEnd, ostream_iterator<int>(cout, " ")); 34 } 35 36 //求差集 set_difference 37 void test03() 38 { 39 vector<int> v1; 40 vector<int> v2; 41 for (int i = 0; i < 10; ++i) 42 v1.push_back(i); 43 for (int i = 5; i < 15; ++i) 44 v2.push_back(i); 45 vector<int> v3(v1.size() + v2.size()); 46 vector<int>::iterator MyEnd = set_difference(v1.begin(), v1.end(), v2.begin(), v2.end(), v3.begin()); 47 copy(v3.begin(), MyEnd, ostream_iterator<int>(cout, " ")); 48 } 49 50 int main(void) 51 { 52 //test01(); 53 //test02(); 54 test03(); 55 return 0; 56 }