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前言

一、力扣121. 买卖股票的最佳时机

class Solution {public int maxProfit(int[] prices) {if(prices == null || prices.length == 0){return 0;}int[][] dp = new int[prices.length][2];dp[0][0] = -prices[0];dp[0][1] = 0;for(int i = 1; i < prices.length; i ++){dp[i][0] = Math.max(dp[i-1][0], -prices[i]);dp[i][1] = Math.max(dp[i-1][1], dp[i-1][0] + prices[i]);}return Math.max(dp[prices.length-1][0], dp[prices.length-1][1]);}
}

二、力扣122.买卖股票的最佳时机II

class Solution {public int maxProfit(int[] prices) {if(prices == null || prices.length == 0){return 0;}int[][] dp = new int[prices.length][2];dp[0][0] = -prices[0];dp[0][1] = 0;for(int i = 1; i < prices.length; i ++){dp[i][0] = Math.max(dp[i-1][0], dp[i-1][1]-prices[i]);dp[i][1] = Math.max(dp[i-1][1], dp[i-1][0]+prices[i]);}return Math.max(dp[dp.length-1][0], dp[dp.length-1][1]);}
}