c++ - Initialization of vector of vectors

Question

vector<vector<int>>dp(3);
for(int i = 0; i<3; i++) {
    vector<int>price(10);
    dp.push_back(price);
}

It is showing error while initialization. Can anyone explain the reason behind this wrong code?

question from:https://stackoverflow.com/questions/65646403/initialization-of-vector-of-vectors

Answer 1

If what you intend is declaring an empty two dimensional vector[3][10], you can do it at once.

#include <iostream>
#include <vector>
int main()
{
    std::vector<std::vector<int>> dp(3,std::vector<int>(10));
    std::cout<<dp.size(); //3
    std::cout<<std::endl<<dp[0].size(); //10
}

Then you can assign values to it by using something like dp[0][4]=12; or with loops.