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LeetCode-714

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题目

Snipaste_2020-12-17_09-17-21.png

结果

Snipaste_2020-12-17_09-17-32.png

代码

DP之二维数组

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

DP之一位数组×2

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class Solution {
    public int maxProfit(int[] prices, int fee) {
        int[] dp1 = new int[prices.length];
        int[] dp2 = new int[prices.length];
        dp2[0] = -prices[0];
        for (int i = 1; i < prices.length; i++) {
            dp1[i] = Math.max(dp1[i - 1], dp2[i - 1] + prices[i] - fee);
            dp2[i] = Math.max(dp2[i - 1], dp1[i - 1] - prices[i]);
        }
        return dp1[prices.length - 1];
    }
}

DP之再优化

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class Solution {
    public int maxProfit(int[] prices, int fee) {
        int a = 0;
        int b = -prices[0];
        for (int i = 1; i < prices.length; i++) {
            a = Math.max(a, b + prices[i] - fee);
            b = Math.max(b, a - prices[i]);
        }
        return a;
    }
}

复杂度

时间复杂度：O（n）

空间复杂度：O（1）