2006. Count Number of Pairs With Absolute Difference K

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problem

solution

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class Solution {
public:
    int countKDifference(vector<int>& nums, int k) {
        sort(nums.begin(), nums.end());
        unordered_map<int,int> mp;
        int count = 0;
        for(int n:nums) mp[n]++;
        int i=0, n=nums.size();
        while(i<n){
            // cout<<nums[i]<<" ";
            if(mp.count(nums[i]+k)) count+= mp[nums[i]]*mp[nums[i]+k];
            
            while(i+1<n && nums[i]==nums[i+1]) i++;
            i++;
        
        }
        return count;
    }
};

analysis

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