LeetCode 122. Best Time to Buy and Sell Stock II

分析

难度 易

来源

https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii/

题目

Say you have an array for which the i^th 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).

Note: You may not engage in multiple transactions at the same time (i.e., you must sell the stock before you buy again).

Example 1:

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.

Example 2:

Input: [1,2,3,4,5]

Output: 4

Explanation: Buy on day 1 (price = 1) and sell on day 5 (price = 5), profit = 5-1 = 4.

             Note that you cannot buy on day 1, buy on day 2 and sell them later, as you are

             engaging multiple transactions at the same time. You must sell before buying again.

Example 3:

Input: [7,6,4,3,1]

Output: 0

Explanation: In this case, no transaction is done, i.e. max profit = 0.

解答

Runtime: 1 ms, faster than 99.60% of Java online submissions for Best Time to Buy and Sell Stock II.

package LeetCode;

public class L122_BestTime2BuyAndSellStockII {
    public int maxProfit(int[] prices) {//允许多次操作，问题相当于求出差值序列中正值之和
        if(prices.length<2)
            return 0;
        int profit=0;
        for (int i = 1; i <prices.length; i++) {
            profit=((prices[i] - prices[i - 1])>0?(profit+(prices[i] - prices[i - 1])):(profit));
        }
        return profit;
    }
    public static void main(String[] args){
        L122_BestTime2BuyAndSellStockII l122=new L122_BestTime2BuyAndSellStockII();
        //int[] prices={7,1,5,3,6,4};
        int[] prices={1,2,3,4,5};
        System.out.println(l122.maxProfit(prices));
    }
}