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  1. import java.util.*;
  2. public class Main{
  3. 	public static int countPairsWithSum(int[] arr,int k){
  4. 		int count=0;
  5. 		Map<Integer,Integer> map=new HashMap<>();
  6. 		for(int j=0;j<arr.length;j++){
  7. 			int complement=k-arr[j];
  8. 			if(map.containsKey(complement)){
  9. 				count++;// or count+=freqMap.get(complement)
  10. 			}
  11. 			map.put(arr[j],map.getOrDefault(arr[j],0)+1);
  12. 		}
  13. 		return count;
  14. 	}
  15. 	public static void main(String[] args){
  16. 		int[] b = {1, 2, 3, 4, 5};
  17.         int k = 6;
  18.         int count = countPairsWithSum(b, k);
  19.  
  20.         System.out.println(count);
  21. 	}
  22. }
Success #stdin #stdout 0.11s 52668KB
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https://ideone.com/m3pzlG
language:
Java (HotSpot 12)
created:
12 days ago
visibility:
public

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