title: Count Pairs Difference Equal K 1
signature: countPairsDifferenceEqualK1 :: [Integer] -> Integer -> Integer -> Integer
  countPairsDifferenceEqualK1 arr n k = 
test_code: import Text.Printf
  import Control.Exception (catch, SomeException)
  import Data.Typeable
  import qualified Data.List as List
  import qualified Data.Map as Map
  import qualified Data.Set as Set
  
  -- SOLUTION CODE
  -- ============================================
  
  PLACEHOLDER_CODE_BODY
  
  -- TESTING CODE 
  -- ============================================
  validateSolution :: Integer -> Integer -> Bool
  validateSolution actual expected = do
      actual == expected
  
  
  driver :: [Integer] -> Integer -> Integer -> Integer -> String
  driver arr n k expected = do
      if (validateSolution (PLACEHOLDER_FN_NAME arr n k) expected)
          then "PASSED"
      else "FAILED"
  
  main = do
      printf "TEST-0...%s\n" (driver ([5, 5, 10, 19, 29, 32, 40, 60, 65, 70, 72, 89, 92]) (7) (12) (0) )
  
      printf "TEST-1...%s\n" (driver ([-98, -90, -88, -82, -80, -78, -74, -74, -72, -62, -58, -58, -56, -52, -48, -46, -38, -38, -30, -12, -10, 4, 8, 8, 14, 22, 24, 26, 36, 40, 40, 48, 56, 58, 58, 58, 60, 62, 64, 68, 68, 74, 84]) (24) (36) (7) )
  
      printf "TEST-2...%s\n" (driver ([0, 0, 1]) (1) (1) (0) )
  
      printf "TEST-3...%s\n" (driver ([1, 7, 13, 14, 16, 29, 34, 42, 44, 49, 59, 62, 65, 66, 70, 71, 73, 73, 76, 80, 96, 96]) (12) (16) (1) )
  
      printf "TEST-4...%s\n" (driver ([-98, -88, -58, -56, -48, -34, -22, -18, -14, -14, -8, -4, -2, 2, 18, 38, 42, 46, 54, 68, 70, 90, 94, 96, 98]) (23) (22) (4) )
  
      printf "TEST-5...%s\n" (driver ([0, 1, 1]) (2) (1) (1) )
  
      printf "TEST-6...%s\n" (driver ([11, 43, 50, 58, 60, 68, 75]) (4) (4) (0) )
  
      printf "TEST-7...%s\n" (driver ([-80, -56, -10, 0, 6, 8, 24, 42, 52, 86, 88, 94]) (11) (9) (0) )
  
      printf "TEST-8...%s\n" (driver ([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]) (29) (30) (0) )
  
      printf "TEST-9...%s\n" (driver ([4, 7, 9, 9, 14, 34, 34, 36, 50, 54, 80, 81, 99]) (9) (8) (0) )
  
source_py: def count_pairs_difference_equal_k_1(arr, n, k):
      count = 0
      arr.sort()
      l = 0
      r = 0
      while (r < n):
          if ((arr[r] - arr[l]) == k):
              count += 1
              l += 1
              r += 1
          elif ((arr[r] - arr[l]) > k):
              l += 1
          else:
              r += 1
      return count
source_cpp: int count_pairs_difference_equal_k_1(vector<int> arr, int n, int k) {
    int count = 0;
    sort(arr.begin(), arr.end());
    int l = 0;
    int r = 0;
    while ( r < n ) {
      if ( arr [ r ] - arr [ l ] == k ) {
        count ++;
        l ++;
        r ++;
      }
      else if ( arr [ r ] - arr [ l ] > k ) l ++;
      else r ++;
    }
    return count;
  }