123. 买卖股票的最佳时机 III

123. 买卖股票的最佳时机 III

和下面的题类似

122. 买卖股票的最佳时机 II

121. 买卖股票最佳时期

var maxProfit = function (prices) {
  var n = prices.length;
  var buy1 = -prices[0];
  var buy2 = -prices[0];
  var sell1 = 0;
  var sell2 = 0;
  for (var i = 1; i < n; i++) {
    buy1 = Math.max(buy1, -prices[i]);
    sell1 = Math.max(sell1, buy1 + prices[i]);
    buy2 = Math.max(buy2, sell1 - prices[i]);
    sell2 = Math.max(sell2, buy2 + prices[i]);
  }
  return sell2;
};