一次遍历,维护最小价格和最大利润

import java.util.*;


public class Solution {
    /**
     * 
     * @param prices int整型一维数组 
     * @return int整型
     */
    public int maxProfit (int[] prices) {
        if(prices.length == 0){
            return 0;
        }
        int max=0,min=prices[0],io;

        for(int i = 0;i<prices.length;i++){
            if(min> prices[i]){
                min = prices[i];
            }
            else if(max < prices[i] - min){
                max = prices[i] - min;
            }
        }
        return max;
    }
}