stock_picker.js

function stockPicker(market) {
  let lowest_index = 0;
  const lowest_previous_index = market.map((x, i) => {
    if (x < market[lowest_index]) {
      lowest_index = i;
    }
    return lowest_index;
  });
  
  let best = {
    high_index: 0,
    low_index: 0,
    profit: 0
  };
  market.forEach((x, i) => {
    const current_profit = x - market[lowest_previous_index[i]];
    if (current_profit > best.profit) {
      best = {
        high_index: i,
        low_index: lowest_previous_index[i],
        profit: current_profit,
      };
    }
  });
  return [best.low_index, best.high_index];
}