LeetCode力扣之121. Best Time to Buy and Sell Stock

最新推荐文章于 2024-08-14 10:48:34 发布

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本文介绍了一种寻找股票买卖最佳时机以获得最大利润的算法。该算法通过一次遍历即可确定买入和卖出的最佳时间点，适用于只允许进行一次交易的情况。文章提供了两种实现方法，并附带示例输入和输出。

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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.

package leetCode;

/**
 * Created by lxw, liwei4939@126.com on 2018/3/25.
 */
public class L121_BestTimeBuySellStock {

    public int maxProfit(int[] prices){
        if (prices.length <=1){
            return 0;
        }
        int maxProfit = 0;
        int lowest = Integer.MAX_VALUE;

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

        return maxProfit;
    }

    //子数组最大和求解法
    public int maxprofit(int[] prices){
        int maxCur = 0, maxSoFar = 0;
        for (int i = 1; i < prices.length; i++){
            maxCur = Math.max(0, maxCur += prices[i] - prices[i-1]);
            maxSoFar = Math.max(maxCur, maxSoFar);
        }
        return maxSoFar;
    }
}