【LEETCODE】37、122题，Best Time to Buy and Sell Stock II

package y2019.Algorithm.array;

/**
 * @ProjectName: cutter-point
 * @Package: y2019.Algorithm.array
 * @ClassName: MaxProfit2
 * @Author: xiaof
 * @Description: 122. Best Time to Buy and Sell Stock II
 * Say you have an array for which the ith element is the price of a given stock on day i.
 * Design an algorithm to find the maximum profit. You may complete as many transactions as you like
 * (i.e., buy one and sell one share of the stock multiple times).
 *
 * Input: [7,1,5,3,6,4]
 * Output: 7
 * Explanation: Buy on day 2 (price = 1) and sell on day 3 (price = 5), profit = 5-1 = 4.
 *              Then buy on day 4 (price = 3) and sell on day 5 (price = 6), profit = 6-3 = 3.
 *
 * 你可以尽可能多的进行交易
 * 那么这个题就是有的赚就买的意思了
 *
 * @Date: 2019/7/2 10:12
 * @Version: 1.0
 */
public class MaxProfit2 {

    public int solution(int[] prices) {
        //那就是贪心算法了
        Integer curSmall = 0, result = 0;
        if(prices.length == 0)
            return 0; //没得赚
        else {
            curSmall = prices[0];
        }

        for(int i = 1; i < prices.length; ++i) {
            int temp = prices[i];

            if(curSmall == null || temp < curSmall) {
                curSmall = temp;
            } else if(temp > curSmall) {
                result += temp - curSmall;
                curSmall = temp;
            }
        }

        return result;
    }

    public static void main(String args[]) {

        int pres[] = {1,2,3,4,5};
        System.out.println(new MaxProfit2().solution(pres));

    }

}