vector

二维向量的输入问题： 

不像二维数组那样，可以直接对 arr[i][j] 进行行循环赋值。在vector<vector<int>>中，因为vector是一个容器，最外层的vector容器中放着更小的vector，而里层的vector里面放的是int型的数字。所以我们首先要对里层的vector容器赋值，然后再把里层的vector作为元素插入到外层的vector中。

vector<vector<int>> array; 则 行 row=array.size( );  列 col=array[0].size( );

#include <iostream>
#include <vector>
 
using namespace std;
 
int main()
{
    vector<vector<int>> test;
    vector<int> v;
    int n,temp;
 
    cin >> n;
    test.clear();
 
    //输入
    for (int i = 0; i<n; i++) {
        v.clear(); 
        for (int j = 0; j < n; j++)
        {
            cin >> temp;
            v.push_back(temp);
        }
        test.push_back(v);
    }
 
    //输出
    for(int i = 0; i < n; i++)
    {
        for(int j = 0;j < n; j++)
{
            cout << test[i][j] << " ";
        }
        cout << endl;
    }
    return 0;
}

#include <iostream>
#include <vector>

using namespace std;

int main(int argc, char *argv[])
{
    vector<vector<int> > vecTest;
    vector<int> vec_int;

    vec_int.push_back(0);
    vec_int.push_back(1);
    vec_int.push_back(2);
    vec_int.push_back(3);

    vecTest.push_back(vec_int);

    auto iter = vecTest.begin();
    for(int i = 0;i<vec_int.size();++i)
    {
        cout << (*iter)[i] << endl;
    }
    return 0;
}

#include <iostream>
#include <vector>

using namespace std;

int main(int argc, char *argv[])
{
    vector<vector<int> > vecTest;
    vector<int> vec_int;
    vector<int> vec_intTest;

    vec_int.push_back(0);
    vec_int.push_back(1);
    vec_int.push_back(2);
    vec_int.push_back(3);

    vec_intTest.push_back(9);
    vec_intTest.push_back(10);
    vec_intTest.push_back(11);
    vec_intTest.push_back(12);

    vecTest.push_back(vec_int);
    vecTest.push_back(vec_intTest);

    auto iter = vecTest.begin();
    for(;iter != vecTest.end(); ++iter)
    {
        for(int i = 0;i<vec_int.size();++i)
        {
            cout << (*iter)[i] << endl;
        }
    }
    return 0;
}