121. Best Time to Buy and Sell Stock

Code

public int maxProfit(int[] prices) {
  int minPrice = prices[0];
  int maxProfit = 0;

  for (int i = 0; i < prices.length; i++) {
    minPrice = Math.min(minPrice, prices[i]);
    maxProfit = Math.max(maxProfit, prices[i] - minPrice);
  }

  return maxProfit;
}