Best Time to Buy and Sell Stock系列

// Best Time to Buy and Sell Stock 1
class Solution {
public:
    int maxProfit(vector<int>& prices) {
        if(prices.size()==0)
            return 0;
        int maxres=prices[prices.size()-1];
        int ans=0;
        for(int i=prices.size()-1;i>=0;i--)
        {
            maxres=max(maxres,prices[i]);
            ans=max(ans,maxres-prices[i]);
        }
        return ans;
        
    }
};

　　

// Best Time to Buy and Sell Stock 2
class Solution {
public:
    int maxProfit(vector<int>& prices) {
        int n=prices.size();
        res=0;
        for(int i=0;i<n-1;i++)
       {
        if(prices[i]<prices[i+1])
        res+=prices[i+1]-prices[i];
       }
       return res;

};