class Solution {
    public int maxProfit(int[] prices) {
        int len = prices.length;
        if(len == 0){
            return 0;
        }
        int[][] dp = new int[len][5];
        dp[0][1] = -prices[0];
        dp[0][3] = -prices[0];
        for(int i = 1; i < len; i++){
            dp[i][1] = Math.max(dp[i-1][1], dp[i-1][0] - prices[i]);
            dp[i][2] = Math.max(dp[i-1][2], dp[i-1][1] + prices[i]);
            dp[i][3] = Math.max(dp[i-1][3], dp[i-1][2] - prices[i]);
            dp[i][4] = Math.max(dp[i-1][4], dp[i-1][3] + prices[i]);
        }
        return dp[len-1][4];
    }
}

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