#include<iostream>
#include<vector>
using namespace std;
vector<vector<int>>construct2DArray(vector<int>& original,int m,int n){
	vector<vector<int>>ans;
	if(original.size() != m * n){
		return ans;
	}
	//auto 这里可以代替 iteration 
	for(auto it = original.begin();it != original.end();it += n){
		// emplace_back;
		ans.emplace_back(it,it+n);
	}
	return ans;
}

int main(){
	vector<int> arr = {1,2,3,4};
	vector<vector<int>>arr1 = construct2DArray(arr,2,2);
	
	for(int i = 0;i < 2;i++){
		for(int j = 0;j < 2;j++){
			cout << arr1[i][j] << " ";
		}
		cout << endl;
	}
	return 0;
	
} 

auto 用法 参考 https://www.zhihu.com/question/35517805

emplace_back() 参考 c++11 之emplace_back 与 push_back的区别_学之知之的博客-CSDN博客_emplace_back