Thread: recursive vector loading

hi,

I was wondering if there is a better way to do the following.

Let say I have a recursive function rec():

Code:

#include <iostream>
#include <vector>
#include <string>
#include <unordered_map>

using namespace std;

void rec(int s, vector<int>& j, unordered_map <int, int>& m){
  
  if (m[s]>0)
    rec(m[s], j, m);
  j.push_back(s);
}



int main (){
  
  vector<int> a(10);

  unordered_map <int, int> map;

  map[1] = 2;
  map[2] = 3;
  map[3] = 4;
  map[5] = 5;

  rec(1,a, map);

  for(int s = 0; s< a.size(); s++){
    cout << a[s] << "\n";
  }

return 0;
}

and in each cycle i need to store the visited map() value. I think the code is clear what I am trying to achieve. however as a result i get:

Code:

0
0
0
0
0
0
0
0
0
0
4
3
2
1

as you can see my numbers are at the end of the vector , which is exactly a behaviour one would expect . but is there a clever way to get those numbers at the begining of the array ?? (remapping as post processing is one way to go but is there a slicker solution ??)

thnx

ps

array needs to be filled with 0 apriori

What array are you talking about? I don't see any arrays in your code.

If you want the values at the beginning of the vector either create an empty vector or stop using push_back() to insert records into the vector.

Jim