LeetCode 121. Best Time to Buy and Sell Stock 原创Java参考解答

LeetCode 121. Best Time to Buy and Sell Stock 原创Java参考解答

问题描述

https://leetcode.com/problems/best-time-to-buy-and-sell-stock/

Say you have an array for which the ith element is the price of a given stock on day i.

If you were only permitted to complete at most one transaction (ie, buy one and sell one share of the stock), design an algorithm to find the maximum profit.

Example 1:

Input: [7, 1, 5, 3, 6, 4]
Output: 5

max. difference = 6-1 = 5 (not 7-1 = 6, as selling price needs to be larger than buying price)

Example 2:

Input: [7, 6, 4, 3, 1]
Output: 0

In this case, no transaction is done, i.e. max profit = 0.

解题思路

题目是求买卖股票的最大收益。

问题的实质是找prices[i2] – prices[i1]差值最大。

prices[i2]为prices数组的最大值, prices[i1]为prices数组的最小值,i1 < i2。

参考代码

public class Solution { 
    public int maxProfit(int[] prices) { 
        if (prices == null || prices.length == 0) { 
            return 0; 
        } 
         
        int maxProfit = 0; 
        int minPrice = Integer.MAX_VALUE; 
        for (int i = 0; i < prices.length; i++) { 
            maxProfit = Math.max(maxProfit, prices[i] - minPrice); 
            minPrice = Math.min(minPrice, prices[i]); 
        } 
         
        return maxProfit; 
    } 
}

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