答案

public class Solution {
    public int maxProfit(int[] prices) {
        if(prices==null||prices.length<=1)
        {
            return 0;
        }
        int currentProfit=0;
        int smallestPrice=prices[0];
        int LEN=prices.length;
        for(int i=1;i<LEN;i++){
            smallestPrice=Math.min(smallestPrice,prices[i]);
            currentProfit=Math.max(currentProfit,prices[i]-smallestPrice);
        }
        return currentProfit;
    }
}

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