C++基础知识

C++ vector（可变长的动态数组）

#include<vector>
#include<algorithm>
#include<iostream>

using namespace std;

int main() 
{
	std::vector<int> myvector;
	int a[10] = { 80,900,1000,1,2,3,4,5,6,7};
	for(int i = 0; i < 10; ++i) {
		myvector.push_back(a[i]);
	}
	for (size_t j=0; j<myvector.size(); ++j) 
	{
		cout << myvector[j] << endl;
	}
	sort(myvector.begin(), myvector.end());
	for (size_t k = 0; k < myvector.size(); ++k) 
	{
		cout << myvector[k] << endl;
	}
	vector<int>::iterator result = find(myvector.begin(), myvector.end(), 7);
	if (result == myvector.end()) 
	{
		cout << "No!" << endl;
	}
	else 
	{
		cout << "Yes!" << endl;
	}
	system("pause");
	return 0;
}

C++实现矩阵乘法

#include<iostream>  
#include<vector> 

using namespace std;

vector<vector<int>> matrix_multiply(vector<vector<int>> arrA, vector<vector<int>> arrB)
{
	//矩阵arrA的行数  
	int rowA = arrA.size();
	//矩阵arrA的列数  
	int colA = arrA[0].size();
	//矩阵arrB的行数  
	int rowB = arrB.size();
	//矩阵arrB的列数  
	int colB = arrB[0].size();
	//相乘后的结果矩阵  
	vector<vector<int>>  res;
	if (colA != rowB)//如果矩阵arrA的列数不等于矩阵arrB的行数。则返回空  
	{
		return res;
	}
	else
	{
		//设置结果矩阵的大小，初始化为为0  
		res.resize(rowA);
		for (int i = 0; i < rowA; ++i)
		{
			res[i].resize(colB);
		}

		//矩阵相乘  
		for (int i = 0; i < rowA; ++i)
		{
			for (int j = 0; j < colB; ++j)
			{
				for (int k = 0; k < colA; ++k)
				{
					res[i][j] += arrA[i][k] * arrB[k][j];
				}
			}
		}
	}
	return res;
}

int main(void)
{
	vector<vector<int>> arrA = { { 2, 1 }, { 4, 3 } };
	vector<vector<int>> arrB = { { 1, 2 }, { 1, 0 } };
	//vector<vector<int>> arrA = { { 1, 2, 3 }, { 4, 5, 6 } };  
	//vector<vector<int>> arrB = { { 1, 4 }, { 2, 5 }, { 3, 6 } };  
	vector<vector<int>> res = matrix_multiply(arrA, arrB);
	//矩阵arrA的行数  
	int rowA = arrA.size();
	//矩阵arrA的列数  
	int colA = arrA[0].size();
	//矩阵arrB的列数  
	int colB = arrB[0].size();
	for (int i = 0; i < rowA; ++i)
	{
		for (int j = 0; j < colB; ++j)
		{
			cout << res[i][j] <<" ";
		}
		cout << endl;
	}
	system("pause");
	return 0;
}

C++实现双向链表

#include<iostream>

using namespace std;

/*双链表结构*/
typedef struct node
{
	int data;
	struct node *prior;
	struct node *next;

}DNode;
/*创建一个带头节点的双链表*/
void CreateDLink(DNode *&head)
{
	int x;
	DNode *p, *s;
	s = (DNode *)malloc(sizeof(DNode));
	if (s == NULL)
	{
		cout << "Fail to malloc the head node!" << endl;

	}
	s->data = 0;
	s->prior = NULL;
	s->next = NULL; //建立一个头结点为head的双链表
	head = s;   //若是循环双向链表则为：s->next=s->prior=s;
	cout << "please input the data of the node" << endl;
	cin >> x;
	while (x != 0)
	{
		p = (DNode *)malloc(sizeof(DNode));
		if (p == NULL)
		{
			cout << "Fail to malloc a new  node!" << endl;

		}

		p->data = x;
		s->next = p;
		p->prior = s;
		p->next = NULL;
		s = p;


		cin >> x;
	}

}

void PrintLink(DNode *head)
{
	if (head->next == NULL)
	{
		cout << "The list is NULL" << endl;
		return;
	}
	DNode *p;
	p = head->next;
	while (p != NULL)
	{
		cout << p->data << " ";
		p = p->next;

	}
	cout << endl;
}
int Length(DNode *head) //求双链表长度
{
	int len = 0;
	DNode * p = head->next;
	while (p != NULL)
	{
		len++;
		p = p->next;
	}
	return len;

}
DNode * Get(DNode *head, int i) //获取链表第i个节点地址
{
	int j = 0;
	DNode *p = head->next;
	while (j < i&&p != NULL)
	{
		p = p->next;
		j++;
	}
	if (p != NULL)
		return p;
	else
		return NULL;
}
int InsertNode(DNode *head, int x, int i)//在第i个位置插入一个节点
{
	DNode *s, *p;
	s = (DNode *)malloc(sizeof(DNode));
	s->data = x;
	if (i == 0)
	{
		s->next = head->next;
		if (head->next != NULL)
			head->next->prior = s;
		s->prior = head;
		head->next = s;

	}
	else
	{
		p = Get(head, i - 1); //查找待插入节点前一个位置
		if (p == NULL)
			return 0;
		else
		{
			s->next = p->next;
			if (p->next != NULL)
				p->next->prior = s;
			s->prior = p;
			p->next = s;
		}
	}

	return 1;
}

void DeleteNode(DNode *head, int index) //删除第index个节点
{
	if (head->next == NULL)
	{
		cout << "The list is NULL" << endl;
		return;
	}
	DNode *p, *s/*保存待删除的节点*/;
	if (index == 0)
	{
		s = head->next;
		head->next = s->next;
		if (s->next != NULL)
			s->next->prior = head;
		free(s);
	}
	else
	{
		p = Get(head, index - 1);
		if (p == NULL)
			cout << "The Node " << index << "is not exist" << endl;
		else
		{
			s = p->next;
			p->next = s->next;
			if (s->next != NULL)
				s->next->prior = p;
			free(s);
		}
	}

}
int main(int argc, char *argv[])
{
	DNode *head;
	CreateDLink(head);
	cout << "链表长度为：" << Length(head) << endl;
	PrintLink(head);
	cout << "第3个节点的值为:" << Get(head, 3)->data << endl;

	cout << "输入插入节点的位置及值：" << endl;
	int value, index;
	cin >> index >> value;
	InsertNode(head, value, index);
	cout << "插入后的链表为：" << endl;
	PrintLink(head);

	cout << "请输入要删除的节点位置：" << endl;
	cin >> index;
	DeleteNode(head, index);
	PrintLink(head);
	return 0;
}