Input element by user into 2D vector c++ - c++

Question

I'a trying to implement an algorithm, i want to input element by the user into 2D vector so that I have an element like this:
reference 1:
1 2 3
3 2 1
1 2 3
so I want to know how to push_back the element into 2D vector
my problem here:
std::vector<vector<int>> d;
//std::vector<int> d;
cout<<"Enter the N number of ship and port:"<<endl;
cin>>in;
cout<<"\Enter preference etc..:\n";
for(i=0; i<in; i++){
cout<<"ship"<<i+1<<":"<<' ';
for(j=0; j<in; j++){
cin>>temp;
d.push_back(temp);// I don't know how to push_back here!!
}
}

Answer 1

Here is the solution
std::vector<vector<int>> d;
//std::vector<int> d;
cout<<"Enter the N number of ship and port:"<<endl;
cin>>in;
cout<<"\Enter preference etc..:\n";
for(i=0; i<in; i++){
cout<<"ship"<<i+1<<":"<<' ';
for(j=0; j<in; j++){
cin>>temp;
d[i].push_back(temp);
}
}

Answer 2

C++ is a strong type language, d is a vector of vector:
for(i=0; i<in; i++){
cout<<"ship"<<i+1<<":"<<' ';
vector<int> row;
for(j=0; j<in; j++){
cin>>temp;
row.push_back(temp);// I don't know how to push_back here!!
}
d.push_back(row);
}

Answer 3

This should work:
vector<vector<int> > d;
int val;
for(int i = 0; i < in; i++){
vector<int> temp;
for(int j = 0; j < in; j++){
cin >> val;
temp.push_back(val);
}
d.push_back(temp);
temp.clear();
}

Answer 4

In general, we can add elements in a 2D matrix of vectors according to a similar approach as mentioned below :
#include<bits/stdc++.h>
using namespace std;
int main() {
int row,col;
cin>>row>>col;
vector<vector<int>>matrix;
for(int i=0;i<row;i++){
vector<int>temp;
for(int j=0;j<col;j++){
int val;
cin>>val;
temp.push_back(val);
}
matrix.push_back(temp);
}
return 0;
}

Answer 5

d[x].push_back(y);
This should work for you.

Answer 6

There are two methods to perform this task:
vector<vector<int> > v;
for(int i=0;i<n;i++){
for(int j=0;j<m;j++){
v[i].push_back(data);
}}
vector<vector<int> > v;
for(int i=0;i<n;i++){
vector<int> x;
for(int j=0;j<m;j++) x[j].push_back(data);
v.push_back(x);
}

Answer 7

/* Below takes user input for n x n array */
vector<vector <int>> arr(n);
for (int i = 0; i < n; i++) {
arr[i].resize(n);
for (int j = 0; j < n; j++) {
cin >> arr[i][j];
}
}

Answer 8

This is what you can do
int in;
std::cout << "Enter the N number of ship and port:" << std::endl;
std::cin >> in;
// declare a vector d of size 'in' containing vectors of size 0;
std::vector<std::vector<int>> d(in, std::vector<int>());
std::cout << "\Enter preference etc..:\n";
for(i=0; i<in; i++){
std::cout << "ship" << i+1 << ":" << ' ';
for(j=0; j<in; j++){
int temp;
std::cin >> temp;
d[i].push_back(temp); // now you can push_back here!!
}
}

Answer 9

#include <iostream>
#include <vector>
using namespace std;
int main() {
int N;
cout << "Please enter the no. of edges: ";
cin >> N;
vector<vector<int>> outer;
for(int i = 0; i < N; i++)
{
vector<int> temp;
for(int j = 0; j < 1; j++)
{
int u, v;
cin >> u;
cin >> v;
temp.push_back(u);
temp.push_back(v);
};
outer.push_back(temp);
temp.clear();
};
for(int i = 0; i<outer.size(); i++)
{
for(int j = 0; j < outer[i].size(); j++)
{
cout<<" "<<outer[i][j];
};
cout<<endl;
};
};

Answer 10

//this is a solution and it litrally works give it a try
//v(n) is must
//thats why your sol was giving problem
//we must specify rows
int main()
{
int value;
vector<vector<int>> v(n);
for(int i=0;i<n;++i)
{
for(int j=0;j<n;++j)
{
cin>>value;
v[i].push_back(value);
}
}
return 0;
}

Answer 11

vector<vector<int>> matrix; //declaring 2D vactor as matrix
int val;
cin>>val; //reading size of matrix in val
for(int i=0;i<val;i++){
vector<int> temp; //make temp vector for storing val for every iteration
for(int j=0;j<val;j++){
int x;
cin>>x;
temp.emplace_back(x);
}
matrix.emplace_back(temp); // push back to matrix, temp vector's all value for every iteration
temp.clear(); // clear temp vector for every iteration
}