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  1. #include<bits/stdc++.h>
  2. #include <iostream>
  3. using namespace std;
  4.  
  5. int countPair(vector<int> arr,int k){
  6.     unordered_map<int,int> freq;
  7.     int count=0;
  8.     for(int i=0;i<arr.size();i++){
  9.  
  10.         if(freq.find(arr[i]+k) != freq.end()){
  11.             count = count+freq[arr[i]+k];
  12.         }
  13.         if(freq.find(arr[i]-k)!=freq.end() && k!=0){
  14.             count += freq[arr[i]-k];
  15.         }
  16.  
  17.         freq[arr[i]]++;
  18.  
  19.     }
  20.     return count;
  21.  
  22. }
  23.  
  24. int main(){
  25.     vector<int> arr={1, 5, 3, 4, 2};
  26.     int k=2;
  27.     cout<<"No. of Pairs: "<<countPair(arr,k);
  28. }
Success #stdin #stdout 0s 5324KB
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stdin
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Standard input is empty
stdout
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No. of Pairs: 3
https://ideone.com/3QjHZC
language:
C++14 (gcc 8.3)
created:
9 days ago
visibility:
public

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