Level 1 (day 5)

第一题

题目链接：https://leetcode.cn/problems/best-time-to-buy-and-sell-stock/

个人题解：线性DP

代码：

class Solution {
public:
    int maxProfit(vector<int>& prices) {
        int minn=INT_MAX,maxx=0;
        for(auto x:prices){
            maxx=max(maxx,x-minn);
            minn=min(minn,x);
        }
        return maxx;
    }
};

第二题

题目链接：https://leetcode.cn/problems/longest-palindrome/

个人题解：贪心，偶数加2，奇数加1

代码：

class Solution {
public:
    int longestPalindrome(string s) {
        unordered_map<char,int> mp;
        for(auto x:s) mp[x]++;
        int res=0;
        for(auto [k,v]:mp){
            res+=v/2*2;
            if(v%2==1 && res%2==0) res++;
        }
        return res;
    }
};