Best Time to Buy and Sell Stock

Source

leetcode:121 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.

思路

首先得到如果第i天卖的话，能够获得的最大收益maxSell[i]，然后取这N个值中的最大值。

maxSell[i] = prices[i] - min

其中，prices[i]表示第i天的价格， min表示第0,...,i-1天中价格的最小值。

Java 代码

public class Solution {
    public int maxProfit(int[] prices) {
        if (prices == null || prices.length == 0 || prices.length == 1)
            return 0;
        if (prices.length == 2){
            if (prices[0] > prices[1])
                return 0;
            return prices[1] - prices[0];
        }

        int min = Integer.MAX_VALUE;
        int max = 0;

        for(int p:prices) {
            min = Math.min(min, p);
            max = Math.max(p-min, max);
        }

        return max;
    }
}