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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6.  
  7. /* Name of the class has to be "Main" only if the class is public. */
  8. class Ideone
  9. {
  10. 	public static void main (String[] args) throws java.lang.Exception
  11. 	{
  12. 		// your code goes here
  13. 		int[] arr = {1,3,2,4};
  14. 		int k = 1;
  15. 		System.out.println("no of good pairs are "+ cntOfGoodPairs(arr,k));
  16. 	}
  17. 	static int cntOfGoodPairs(int[] arr, int k){
  18. 		HashMap<Long,Long> map = new HashMap<>();
  19. 		map.put(0L,1L);
  20. 		long[] prefix = new long[arr.length];
  21. 		prefix[0] = arr[0];
  22. 		int cnt = 0;
  23. 		for(int i =1;i<arr.length;i++){
  24. 			prefix[i] = prefix[i-1]+arr[i];
  25. 		}
  26. 		for(int j=0;j<arr.length;j++){
  27. 			long modPrefix = ((prefix[j]%k -j%k+k)%k);
  28. 			cnt+=map.getOrDefault(modPrefix, 0L);
  29. 			map.put(modPrefix,map.getOrDefault(modPrefix, 0L)+1);
  30. 		}
  31. 		return cnt;
  32.  
  33. 	}
  34. }
Success #stdin #stdout 0.1s 53512KB
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Standard input is empty
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no of good pairs are 10
https://ideone.com/21Urj7
language:
Java (HotSpot 12)
created:
2 days ago
visibility:
public

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