2190. Most Frequent Number Following Key In an Array

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problem

solution

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class Solution {
public:
    int mostFrequent(vector<int>& nums, int key) {
        int  n=nums.size();
        unordered_map<int,int> mp;
        for(int i=0;i<n-1;++i){
            if( nums[i] == key){
                mp[nums[i+1]]++;
            }
        }
        int target = 0, freq = 0;
        for(auto m:mp){
            if(m.second >freq){
                freq = m.second;
                target = m.first;
            }
        }
        
        return target;
        
    }
};

analysis

  • time complexity O(n)
  • space complexity O(n)