打印向量中的值

Question

I know the reason why this is happening but don't know how to solve this as I am new to STL.

I am taking the inputs from the user and representing the weighted graph using vectors. I declared a vector pair<int,int> to store the value of the edge and the weight.

#include<iostream>
#include<vector>
using namespace std;
int main()
{
    int n,m,c;
    cout<<"Enter n,m : "<<endl;
    cin>>n>>m;
    vector<pair<int,int>> adj[n+1];
    cout<<"If un-directed input 1 else input 0: "<<endl;
    cin>>c;
    cout<<"Enter the values of u,v and the waight : "<<endl;
    for(int i=0;i<m;i++)
    {
        int u,v,w;
        cin>>u>>v>>w;
        adj[u].push_back({v,w});
        if(c==1)
            adj[v].push_back({u,w});
    }
    for(int i=0;i<=n;i++)
    {
        for(int j:adj[i])
        {
            cout<<i<<"->" << j <<endl;
        }
        cout<<endl;
    }
    cout<<"Inserted Successfully";
    return 0;
}

But when i am printing the values i am not able to compile the program. It is due to this for loop.

for(int j:adj[i])
        {
            cout<<i<<"->" << j <<endl;
        }

As the value in adj[i] is a pair of edge and weight thus ,the for_each loop is unable to convert the pair value to a single int value. This might be the reason but i am unable to solve this as i am new to the STL.

Please Help.

Answer 1

j is a pair of int in order to access the first/second int you have to use j.first/ j.second

    for(pair<int,int> j:adj[i])
    {
        cout<<i<<"->" << j.second <<endl;
    }