121

题意：给定序列，找出max(prices[j] - prices[i]) ( j > i) 

动态规划  ： local = max ( local + prices[i+1] - prices[i]， 0）;

class Solution {
public:
    int maxProfit(vector<int>& prices) {
        if (prices.empty()) return 0; //需要单独判空
        int local=0,golal = 0;
        for (int i=0; i<prices.size()-1; i++)
        {
            local = max(local + (prices[i+1] - prices[i]), 0);
            golal = max(golal,local);
        }
        return golal;
    }
};