Java 代码

class Solution {
    public int maxProfit(int[] prices) {
        // dp[i][0]：持有1股的最大利润
        // dp[i][1]: 持有0股当天卖掉
        // dp[i][2]: 持有0股非当天卖掉
        // dp[i][0] = max(dp[i - 1][0], dp[i - 1][2] - prices[i])
        // dp[i][1] = dp[i - 1][0] + prices[i]
        // dp[i][2] = max(dp[i - 1][1], dp[i - 1][2])
        // dp[0][0] = 0 - prices[0]
        // dp[0][1] = 0
        // dp[0][2] = 0
        int n = prices.length;
        if (n == 0) return 0;
        int[][] dp = new int[n][3];
        dp[0][0] = 0 - prices[0];
        for (int i = 1; i < n; ++i) {
            dp[i][0] = Math.max(dp[i - 1][0], dp[i - 1][2] - prices[i]);
            dp[i][1] = dp[i - 1][0] + prices[i];
            dp[i][2] = Math.max(dp[i - 1][1], dp[i - 1][2]);
        }

        return Math.max(dp[n - 1][1], dp[n - 1][2]);
    }
}