Best Time to Buy and Sell Stock III

最新推荐文章于 2024-01-20 11:34:17 发布

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本文介绍了一种算法，用于计算给定股票价格数组中通过至多两笔交易获得的最大利润。该算法采用动态规划思想，分为左右两个阶段进行计算，最终找到最大收益组合。

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

Design an algorithm to find the maximum profit. You may complete at most two transactions.

Note:
You may not engage in multiple transactions at the same time (ie, you must sell the stock before you buy again).

Left[i] means for current day i, best buy and sell value between 0~i;

right[i] means for current day i, best buy and sell value between i~length-1.

public class Solution {
    public int maxProfit(int[] prices) {
		// Start typing your Java solution below
		// DO NOT write main() function
		if(prices.length < 2)
			return 0;
		int[] left = new int[prices.length];
		int[] right = new int[prices.length];
		int minVal = prices[0];
		int maxVal = prices[prices.length - 1];
		int res = 0;
		for(int i = 1; i < prices.length; i++){
			minVal = Math.min(minVal, prices[i]);
			left[i] = Math.max(left[i - 1], prices[i] - minVal);
		}
		for(int i = prices.length - 2; i >= 0; i --){
			maxVal = Math.max(maxVal, prices[i]);
			right[i] = Math.max(right[i + 1], maxVal - prices[i]);
		}
		for(int i = 0; i < prices.length; i++){
			res = Math.max(res, left[i] + right[i]);
		}
		return res;
	}
}