title: inserting into vectors c++
body: <p>I need to push 66,000 vectors (the number of vectors is not fixed, it can be 90,000 vectors also. For the sake of brevity I am showing the below code with the example of 66,000 vectors) of type vector into the following vector:</p>
  
  <pre><code>vector&lt;int&gt; vec;
  </code></pre>
  
  <p>The size of each of the 66,000 vectors is 9,000 elements. I am using the following for doing the same:</p>
  
  <pre><code>vec.reserve(66000*9000);
  for(int j=0;j&lt;66000;j++)
      for(int i=0;i&lt;9000;i++) //9000 elements in vec1[i] per vector is not fixed
          vec.push_back(vec1[i]); //i am pushing i as an example
  </code></pre>
  
  <p>Is there someway by which I may increase the efficiency of this code?</p>
  
  <p>I need to concatenate too many vectors, so a solution for the same is potentially different from concatenating two vectors. Also I can not use multi-threading as mentioned in the previous question</p>