代码随想录算法打卡第四十三天, 新手自我记录一下刷题历程, 仅为自我打卡使用.

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123. 买卖股票的最佳时机 III

class Solution {
public:
    int maxProfit(vector<int>& prices) {
        vector<vector<int>> dp(prices.size(), {0, 0, 0, 0, 0});
        dp[0][1] = -prices[0];
        dp[0][3] = -prices[0];
        for (int i = 1; i < prices.size(); ++i) {
            dp[i][0] = dp[i - 1][0];
            dp[i][1] = max(dp[i - 1][1], dp[i - 1][0] - prices[i]);
            dp[i][2] = max(dp[i - 1][2], dp[i - 1][1] + prices[i]);
            dp[i][3] = max(dp[i - 1][3], dp[i - 1][2] - prices[i]);
            dp[i][4] = max(dp[i - 1][4], dp[i - 1][3] + prices[i]); 
        }
        return dp.back()[4];
    }
};

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188. 买卖股票的最佳时机 IV

class Solution {
public:
    int maxProfit(int k, vector<int>& prices) {
        vector<vector<int>> dp(prices.size(), vector<int>(2 * k + 1, 0));
        for (int i = 1; i < 2 * k + 1; i += 2) dp[0][i] = -prices[0];

        for (int i = 1; i < prices.size(); ++i) {
            for (int j = 1; j < 2 * k + 1; j += 2) {
                dp[i][j] = max(dp[i - 1][j], dp[i - 1][j - 1] - prices[i]);
                dp[i][j + 1] = max(dp[i - 1][j + 1], dp[i - 1][j] + prices[i]);
            }
        }
        return dp.back()[2 * k];
    }
};

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希望还能再坚持一天!