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  1. import java.util.*;
  2.  
  3. class Main {
  4.     public static int countPairs(int[] nums, int target) {
  5.         Map<Integer, Integer> map = new HashMap<>();
  6.         int cnt=0;
  7.  
  8.         for (int i = 0; i < nums.length; ++i) {
  9.  
  10.             // abs(nums[i] - nums[j]) == target 
  11.             // ----> nums[i] = nums[j] + target
  12.             // ----> nums[i] = nums[j] - target
  13.  
  14.             int num=target+nums[i];
  15.             if(map.containsKey(num)){
  16.                 cnt+=map.get(num);
  17.             }
  18.  
  19.             num=nums[i]-target;
  20.             if(map.containsKey(num)){
  21.                 cnt+=map.get(num);
  22.             }
  23.  
  24.             map.put(nums[i], map.getOrDefault(nums[i],0)+1);
  25.         }
  26.         return cnt;
  27.     }
  28.  
  29.     public static void main(String[] args) {
  30.         Scanner sc=new Scanner(System.in);
  31.         int n=sc.nextInt();
  32.         int[] nums = new int[n];
  33.         for(int i=0;i<n;i++){
  34.             nums[i]=sc.nextInt();
  35.         }
  36.         int target = sc.nextInt();
  37.         int count=countPairs(nums,target);
  38.         System.out.println("Number of pairs with absolute difference "+target+" : "+count);
  39.         sc.close();
  40.     }
  41. }
  42.  
Success #stdin #stdout 0.23s 60832KB
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Number of pairs with absolute difference 2 : 3
https://ideone.com/t4yy2x
language:
Java (HotSpot 12)
created:
3 days ago
visibility:
public

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