最标准答案

 

不可以有前一项的影响，只能用来对比并不叠加

 

这里max设置0就会导致先行进入大于max的判断语句！

 

 无语了，自己把问题想的太复杂了！

class Solution {
    public int maxProfit(int[] prices) {
        if(prices.length<2) return 0;
        int[] value = new int[prices.length];
        int max,min;
        value[0] = 0;
        value[1] = prices[1]>prices[0] ?
        prices[1]-prices[0] : 0;
        if(prices[0]>prices[1]){
            max = prices[1]; min = prices[1];
        }
        else{
            max = prices[1]; min = prices[0];
        }
        for(int i = 2;i < prices.length;i++){
            if(prices[i] > max){
                max = prices[i];
                value[i] = max - min;
            }
            else if(prices[i] < min){
                min = prices[i];
                value[i] = value[i-1];
            }
            else{
                 value[i] = value[i-1] > prices[i]-min?
                 value[i-1]:prices[i]-min;
            }
        }
        int res = 0;
        for(int i = 0; i < prices.length;i++){
            if(value[i] > res)  res = value[i];
        }
        return res;
    }
}