vector构造函数通常含有两个参数 

原型如下:

 vector( size_type num, const TYPE &val );

  • 数量(num)和值(val) - 构造一个初始放入num个值为val的元素的Vector

 方法1:

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

int main(){
int m, n;
cin >> m >> n ;
vector<vector<int>> v1(m, vector<int>(n,123));
for (int i = 0; i < m; i++){
for (int j = 0; j < n; j++)
cout << v1[i][j];
cout << endl;
}
return 0;
}

当然也可以这样:

int N=5, M=6; 
vector<vector<int> > Matrix(N);
for(int i =0; i< Matrix.size(); i++){
Matrix[i].resize(M);
}