Problem122.java

class Problem122 {
 public static void main(String[] args) {
 int[] prices = {7,1,5,3,6,4};
 int res = new Problem122().maxProfit(prices);
 System.out.println(res);
 }

 public int maxProfit(int[] prices) {
 int buy_pos = 0;
 int sale_pos = 0;
 int profit = 0;
 for (int i = 1; i < prices.length; i++) {
 if (prices[i] >= prices[sale_pos]) {
 //递增趋势
 sale_pos = i;
 } else { //递减趋势
 if (sale_pos > buy_pos) { 
 profit += (prices[sale_pos] - prices[buy_pos]);
 }
 buy_pos = i;
 sale_pos = i;
 }
 }

 if (sale_pos > buy_pos) {
 profit += (prices[sale_pos] - prices[buy_pos]);
 } 
 return profit;
 }
}