20220420, 1min

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```javascript // 08:54 -> 08:55 // 贪心，每天的正利润相加 var maxProfit = function(prices) { let profit = 0; for (let i = 1; i < prices.length; i++) { profit += Math.max(0, prices[i] - prices[i-1]) } return profit; };

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  5. <a name="NF72s"></a>
  6. ## 20220419, 5min
  7. | <br />```javascript
  8. /**
  9.  * @param {number[]} prices
  10.  * @return {number}
  11.  */
  12.  // 13:49 -> 13:54
  13. var maxProfit = function(prices) {
  14.   let maxProfit = 0;
  15.   for (let i = 1; i < prices.length; i++) {
  16.     // maxProfit += (prices[i] - prices[i - 1]) //  bug：当天比昨天的价格低的话，可以选择不卖出，所以需要判断利润是否大于0
  17.     // const profit = prices[i] - prices[i - 1] // bug：assignment to constant variable
  18.     let profit = prices[i] - prices[i - 1]
  19.     profit = profit > 0 ? profit : 0;
  20.     maxProfit += profit; 
  21.   }
  22.   return maxProfit;
  23. };

知识点
- Math.max(0, prices[i] - prices[i - 1]);是let profit = prices[i] - prices[i - 1]; profit = profit > 0 ? profit : 0;的更简单的写法
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