1887. Reduction Operations to Make the Array Elements Equal

class Solution {
public:
    int reductionOperations(vector<int>& nums) {
        unordered_map<int,int>mp;
        sort(nums.begin(),nums.end());
        int n=nums.size();
        if(n<2) return 0;

        for(auto i:nums){
            mp[i]++;
        }
        long long count=0;
        int j=0;
        for(int i=0;i<n;i++){
            while(nums[i]==nums[i+1] and i<n) i++;

            count+=mp[nums[i]]*j;
            j++;

        }

        return count;
    }
};