leetcode 904.水果成篮

class Solution {
    public:
        int totalFruit(vector<int>& fruits) {
            int left=0;
            int length=fruits.size();
            map<int,int> mpt;
            int ans=0;
            for(int right=0;right<fruits.size();right++){
                mpt[fruits[right]]++;
                while(mpt.size()>2){
                    auto it=mpt.find(fruits[left]);
                    it->second--;
                    if(it->second==0){
                        mpt.erase(it);
                    }
                    ++left;
                }
                ans=max(ans,right-left+1);
            }
            return ans;


        }
    };