java逻辑清晰题解 空间负责度1

时间复杂度O(n)

空间复杂度O(1)

import java.util.*;

public class Solution {
  
    public int maxProfit (int[] prices) {
        // 已卖0次 持有股票
        int zeroY = -prices[0];
	  // 已卖1次 无股票
        int oneN = -1;
	  // 已卖1次 持有股票
        int oneY = Integer.MIN_VALUE;
        int result = 0;
        for (int i = 1; i < prices.length; i++) {
            if (oneN != -1) {
                result = Math.max(result, oneY + prices[i]);
                oneY = Math.max(oneY, oneN - prices[i]);
            }
            oneN = Math.max(oneN, zeroY + prices[i]);
            result = Math.max(result, oneN);
            zeroY = Math.max(zeroY, -prices[i]);
        }
        return result;
    }
}