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  1. import java.util.*;
  2.  
  3. public class Main {
  4.     static int countPairsWithSum(int[] b, int k) {
  5.         int count = 0;
  6.         Map<Integer, Integer> seen = new HashMap<>();
  7.  
  8.         for (int j = 0; j < b.length; ++j) {
  9.             int complement = k - b[j];
  10.             if (seen.containsKey(complement)) {
  11.                 count++;
  12.             }
  13.             seen.put(b[j], j);
  14.         }
  15.  
  16.         return count;
  17.     }
  18.  
  19.     public static void main(String[] args) {
  20.         int[] b = {1, 2, 3, 4, 5};
  21.         int k = 6;
  22.         int count = countPairsWithSum(b, k);
  23.  
  24.         System.out.println("Count of pairs with sum " + k + " is: " + count);
  25.     }
  26. }
Success #stdin #stdout 0.18s 57428KB
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Standard input is empty
stdout
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Count of pairs with sum 6 is: 2
https://ideone.com/OkWvBV
language:
Java (HotSpot 12)
created:
5 days ago
visibility:
public

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