Puzzle : Find the best time to buy and sell a stock from a list of values in an array

void StockProcess(const vector<int>& stocks,
                                  int* buyday,
                                  int* sellday)
{
        int min_index = 0;
        *buyday = 0;
        *sellday = 0;
        for (int i = 1; i < stocks.size(); ++i) {
              if (stocks[i] < stocks[min_index]) {
                    min_index = i;
              } else if ( (stocks[i] - stocks[min_index]) > (stocks[*sellday] - stocks[*buyday])) {
                   *buyday = min_index;
                   *sellday = i;
             }
        }
}