leetcode每日刷题计划-简单篇day11

Num 121 买卖股票的最佳时期 Best Time to Buy and Sell Stock

class Solution {
public:
    int maxProfit(vector<int>& prices) {
        int len=prices.capacity();
        if(prices.capacity()==) return ;
        int minn=prices[];
        int maxn=prices[];
        int ans=;
        for(int i=;i<=len-;i++)
        {
            maxn=prices[i];
            minn=prices[i];
            for(int j=i+;j<=len-;j++)
            {
                if(prices[j]>maxn)
                    maxn=prices[j];
            }
            ans=max(ans,maxn-minn);
        }
        return ans;
    }
};

Num 122 买卖股票的最佳时期 || Best Time to Buy and Sell Stock ||

先上一个正确但是TLE的方法。。。

class Solution {
public:
    int maxProfit(vector<int>& prices) {
        int ans[];
        int len=prices.capacity();
        if(len==||len==) return ;
        memset(ans,,sizeof(ans));
        if(len==) return max(,prices[]-prices[]);
        ans[len-]=max(,(int)(prices[len-]-prices[len-]));
        for(int j=len-;j>=;j--)
        {
            for(int i=;i<len--j;i++)
            {
                ans[j]=max(ans[j],max(ans[j+i],ans[j+i]+(int)(prices[j+i]-prices[j])));
            }
        }
        return ans[];
    }
};

TLE 代码

默认里面带的max函数只能处理两个

另外这道题是贪心，刚开始重复计算tle了

class Solution {
public:
    int maxProfit(vector<int>& prices) {
        int ans=;
        int len=prices.capacity();
        for(int i=;i<len-;i++)
            ans=ans+max(,prices[i+]-prices[i]);
        return ans;
    }
};