力扣-2190题 数组中紧跟key之后出现最频繁的数字（C++）- 哈希

题目链接：https://leetcode-cn.com/problems/most-frequent-number-following-key-in-an-array/
题目如下：

class Solution {
public:
    int mostFrequent(vector& nums, int key) {
        map umap;
        bool flag=false;

        for(int i=0;i
            if(nums[i]==key) { //这里要理解题意
                umap[nums[i+1]]++;
            }                
        }

        int res=0,cnt=0;
        for(auto e:umap){
            if(e.second>cnt){
                res=e.first;
                cnt=e.second;
            }
        }

        return res;
    }
};