Vector

下面是vector的基础使用方法。

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


int main(){
	vector<int> vec;
	vec.push_back(1);
	vec.push_back(2);
	vec.push_back(3);
	for (int i = 0; i < vec.size(); i++){
		cout << vec[i] << endl;
	}
	// 清空vec内数据 
	vec.clear();
	for (int i = 0; i < vec.size(); i++){
		cout << vec[i] << endl;
	}
	// 清除vec的内存 
	vector<int>().swap(vec);
	return 0;
}

同样结构体也是可以的

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


struct Student{
	string name;
	int age;
}; 

int main(){
	vector<Student>v;
	Student stu1, stu2;
	stu1.name = "玛卡巴卡";
	stu1.age = 10;
	stu2.name = "胖橙";
	stu2.age = 20;
	v.push_back(stu1);
	v.push_back(stu2);
	for (int i = 0; i < v.size(); i++){
		cout << v[i].name << " " << v[i].age << endl;
	}
	return 0;
}

下面是快速初始化，构造的方式，vectorv中的第一个参数是长度大小。第二个参数是初始值。

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

int main(){
	int n;
	cin >> n;
	vector<int>v(n, 0);

	for (int i = 0; i < v.size(); i++){
		cout << v[i] << endl;
	}
	return 0;
}

二维的解决方法：

int n = 5;
vector<vector<int> > vec2;
for (int i = 0; i < vec2.size(); i++){
	vector<int> x(i + 1, 1);
	vec2.push_back(x);
}

二维的初始化

int main(){
	int n = 10, m = 5;
	vector<vector<int> > vec(n, vector<int>(m, 0));
	for (int i  = 0; i < n; i++){
		for (int j = 0; j < m; j++){
			cout << vec[i][j] << " ";
		}
		cout << endl; 
	}
	return 0;
}