Maximum profit of jz63 shares

Suppose you store the price of a stock in an array in chronological order , What's the maximum profit you can get from buying and selling this stock at one time ？

Input : [7,1,5,3,6,4]
Output : 5
explain : In the 2 God （ Stock price = 1） Buy when , In the 5 God （ Stock price = 6） Sell when , Maximum profit = 6-1 = 5 .
      Note that profit cannot be 7-1 = 6, Because the selling price needs to be higher than the buying price .

Ideas ：

Let's suppose we buy stocks ourselves . as time goes on , Every day we can choose whether to sell shares or not . that , Suppose it's in i God , If we want to sell shares today , So how much money can we make ？

obviously , If we're really buying and selling stocks , We will definitely think ： If only I had bought stocks at an all-time low ！ Great , In the title , We just use a variable to record a historical lowest price minprice, We can assume that our stock was bought on that day . So we're in the second i The profit from selling stocks in one day is prices[i] - minprice.

therefore , We just need to traverse the price array once , Record the lowest point in history , Then think about such a problem every day ： If I bought at the lowest point in history , So how much money can I make from selling today ？ When all days are considered , We got the best answer .

Implementation code

public int maxProfit(int[] prices) {
        int maxProfit = 0;
        int minPrice = Integer.MAX_VALUE;
        for(int i = 0; i < prices.length;i++){
            if(prices[i] < minPrice){
                minPrice  = prices[i];
            }
            else if(prices[i] - minPrice > maxProfit){
                maxProfit = prices[i] - minPrice;
            }
        }
        return maxProfit;
    }