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).
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:7Explanation: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:4Explanation: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:0Explanation:In this case, no transaction is done, i.e. max profit = 0.
与121不同的是，你可以做多次股票交易，但一定要卖完才能再次购买。
从解题思路来说，我们只需要从第二天开始，如果当前价格比之前价格高，则把差值加入利润中，因为我们可以昨天买入，今日卖出，若明日价更高的话，还可以今日买入，明日再抛出。以此类推，遍历完整个数组后即可求得最大利润。
int maxProfit(vector<int>& prices) {
int res = 0;
if(prices.size() == 0) return res;
for(int i=0; i<prices.size()-1; i++){
if(prices[i+1] > prices[i]){
res += prices[i+1] - prices[i];
}
}
return res;
}
