3-PARTITION problem

Question

here is another dynamic programming question (Vazirani ch6)

Consider the following 3-PARTITION problem. Given integers a1...an, we want to determine whet

Answer 1

As I have answered in same another question like this, the C++ implementation would look something like this:

int partition3(vector &A)
{
  int sum = accumulate(A.begin(), A.end(), 0);
  if (sum % 3 != 0)
  {
    return false;
  }
  int size = A.size();

  vector> dp(sum + 1, vector(sum + 1, 0));
  dp[0][0] = true;

  // process the numbers one by one
  for (int i = 0; i < size; i++)
  {
    for (int j = sum; j >= 0; --j)
    {
      for (int k = sum; k >= 0; --k)
      {
        if (dp[j][k])
        {
          dp[j + A[i]][k] = true;
          dp[j][k + A[i]] = true;
        }
      }
    }
  }
  return dp[sum / 3][sum / 3];
}