【LeetCode】 121. Best Time to Buy and Sell Stock 买卖股票的最佳时机（Easy）（JAVA）
题目地址: https://leetcode.com/problems/best-time-to-buy-and-sell-stock/
题目描述：
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 (i.e., buy one and sell one share of the stock), design an algorithm to find the maximum profit.
Note that you cannot sell a stock before you buy one.
Example 1:
Input: [7,1,5,3,6,4]
Output: 5
Explanation: Buy on day 2 (price = 1) and sell on day 5 (price = 6), profit = 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
Explanation: In this case, no transaction is done, i.e. max profit = 0.
题目大意
给定一个数组，它的第 i 个元素是一支给定股票第 i 天的价格。
如果你最多只允许完成一笔交易（即买入和卖出一支股票），设计一个算法来计算你所能获取的最大利润。
注意你不能在买入股票前卖出股票。
解题方法
1、对数组元素进行遍历
2、用一个 min 值来记录当前最小的值，作为买点
3、当前值 - min 是否大于 max，判断是否记录下来
class Solution {
public int maxProfit(int[] prices) {
if (prices.length <= 0) return 0;
int max = 0;
int min = prices[0];
for (int i = 0; i < prices.length; i++) {
if ((prices[i] - min) > max) max = prices[i] - min;
if (prices[i] < min) min = prices[i];
}
return max;
}
}
执行用时 : 1 ms, 在所有 Java 提交中击败了 99.59% 的用户
内存消耗 : 42.7 MB, 在所有 Java 提交中击败了 5.02% 的用户
