## [Hackerrank] Pairs

Jan 10

You will be given an array of integers and a target value. Determine the number of pairs of array elements that have a difference equal to a target value.

- Add all elements to a Set
- To figure if an element arr[i] and some X make a pair, we check if

(arr[i] – Target) is in Set**why?**

arr[i] – X = Target

X = arr[i] – Target

// Complete the pairs function below. static int pairs(int k, int[] arr) { Set<Integer> arrSet = new HashSet<Integer>(); for ( int i = 0 ; i < arr.length ; i++ ) arrSet.add(arr[i]); int ret = 0; for ( int i = 0 ; i < arr.length ; i++ ) if (arrSet.contains(arr[i]-k)) ret++; return ret; } |

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