C++ Research and Development of Generic Programming Lecture 16 [Common Sorting Algorithms]

One, sort

Function description:

• Sort the elements in the container

Function prototype:

• sort(iterator beg, iterator end, _Pred);

  // Find the element by value, find the iterator to return to the specified position, find the iterator to return to the end position

  // beg starts iterator

  // end ends the iterator

  // _Pred predicate

Example:

#include <algorithm>
#include <vector>

void myPrint(int val)
{
	cout << val << " ";
}

void test01() {
	vector<int> v;
	v.push_back(10);
	v.push_back(30);
	v.push_back(50);
	v.push_back(20);
	v.push_back(40);

	//sort默认从小到大排序
	sort(v.begin(), v.end());
	for_each(v.begin(), v.end(), myPrint);
	cout << endl;

	//从大到小排序
	sort(v.begin(), v.end(), greater<int>());
	for_each(v.begin(), v.end(), myPrint);
	cout << endl;
}

int main() {

	test01();

	system("pause");

	return 0;
}

**Summary:**sort is one of the most commonly used algorithms in development and requires proficiency

二、random_shuffle

Function description:

• Shuffle the elements within the specified range and adjust the order randomly

Function prototype:

• random_shuffle(iterator beg, iterator end);

  // Randomly adjust the order of elements in the specified range

  // beg starts iterator

  // end ends the iterator

  ​

Example:

#include <algorithm>
#include <vector>
#include <ctime>

class myPrint
{
public:
	void operator()(int val)
	{
		cout << val << " ";
	}
};

void test01()
{
	srand((unsigned int)time(NULL));
	vector<int> v;
	for(int i = 0 ; i < 10;i++)
	{
		v.push_back(i);
	}
	for_each(v.begin(), v.end(), myPrint());
	cout << endl;

	//打乱顺序
	random_shuffle(v.begin(), v.end());
	for_each(v.begin(), v.end(), myPrint());
	cout << endl;
}

int main() {

	test01();

	system("pause");

	return 0;
}

Summary: random_shuffle shuffle algorithm is more practical, remember to add random number seed when using

Three, merge

Function description:

• Two container elements are merged and stored in another container

Function prototype:

• merge(iterator beg1, iterator end1, iterator beg2, iterator end2, iterator dest);

  // The container elements are merged and stored in another container

  // Note: The two containers must be in order

  // beg1 container 1 start iterator
  // end1 container 1 end iterator
  // beg2 container 2 start iterator
  // end2 container 2 end iterator
  // dest target container start iterator

  ​

Example:

#include <algorithm>
#include <vector>

class myPrint
{
public:
	void operator()(int val)
	{
		cout << val << " ";
	}
};

void test01()
{
	vector<int> v1;
	vector<int> v2;
	for (int i = 0; i < 10 ; i++) 
    {
		v1.push_back(i);
		v2.push_back(i + 1);
	}

	vector<int> vtarget;
	//目标容器需要提前开辟空间
	vtarget.resize(v1.size() + v2.size());
	//合并  需要两个有序序列
	merge(v1.begin(), v1.end(), v2.begin(), v2.end(), vtarget.begin());
	for_each(vtarget.begin(), vtarget.end(), myPrint());
	cout << endl;
}

int main() {

	test01();

	system("pause");

	return 0;
}

Summary: The two containers merged by merge must be in an orderly sequence and need to open up space.

Four, reverse

Function description:

• Reverse the elements in the container

Function prototype:

• reverse(iterator beg, iterator end);

  // Reverse the elements in the specified range

  // beg starts iterator

  // end ends the iterator

  ​

Example:

#include <algorithm>
#include <vector>

class myPrint
{
public:
	void operator()(int val)
	{
		cout << val << " ";
	}
};

void test01()
{
	vector<int> v;
	v.push_back(10);
	v.push_back(30);
	v.push_back(50);
	v.push_back(20);
	v.push_back(40);

	cout << "反转前： " << endl;
	for_each(v.begin(), v.end(), myPrint());
	cout << endl;

	cout << "反转后： " << endl;

	reverse(v.begin(), v.end());
	for_each(v.begin(), v.end(), myPrint());
	cout << endl;
}

int main() {

	test01();

	system("pause");

	return 0;
}