title: Find Repetitive Element 1 N 1
signature: func findRepetitiveElement1N1(arr []int, n int) int {
test_code: package main
  
  import (
      "fmt"
      "reflect"
      "math"
      "sort"
  )
  
  // SOLUTION CODE
  // ===================================
  PLACEHOLDER_CODE_BODY
  
  // TESTING CODE
  // ===================================
  func validateSolution(actual int, expected int) bool {
      return reflect.DeepEqual(actual,expected)
  }
  
  func driver(arr []int, n int, expected int) string {
      if validateSolution(PLACEHOLDER_FN_NAME(arr, n),expected) {
              return "PASSED"
      }
      return "FAILED"
  
  }
  
  func main() {
  
      // Use imports to avoid undefined errors
      var _ = reflect.DeepEqual
      _ = math.Abs
      _ = sort.Sort
      result := ""
      result = driver([]int{4, 8, 27, 34, 39, 42, 43, 54, 72}, 
  	5, 313)
      fmt.Printf("TEST-0...%s\n", result)
      
      result = driver([]int{-38, -66, -38, -48, -96, 74, -32, -62, -34, -32, -88, -12, -8, -4}, 
  	9, -520)
      fmt.Printf("TEST-1...%s\n", result)
      
      result = driver([]int{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1}, 
  	8, -23)
      fmt.Printf("TEST-2...%s\n", result)
      
      result = driver([]int{88, 86, 23, 81, 76, 16, 94, 64, 59, 50, 71, 62, 10, 89, 73, 64, 65, 96, 83, 40, 99, 40, 77, 33, 14, 62, 6, 89, 74, 96, 93, 29, 15, 93, 9, 58, 98, 76, 23, 23, 70, 99}, 
  	31, 2101)
      fmt.Printf("TEST-3...%s\n", result)
      
      result = driver([]int{-96, -94, -82, -64, -56, -40, -36, -34, -32, -24, -24, -22, -20, -20, -20, -18, -18, -12, -10, -6, 16, 20, 20, 22, 26, 30, 36, 46, 46, 50, 50, 52, 64, 64, 64, 68, 72, 74, 76, 92, 96, 98}, 
  	28, 76)
      fmt.Printf("TEST-4...%s\n", result)
      
      result = driver([]int{0, 1, 1, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1}, 
  	25, -288)
      fmt.Printf("TEST-5...%s\n", result)
      
      result = driver([]int{2, 6, 7, 13, 19, 23, 37, 39, 42, 42, 43, 45, 52, 53, 55, 56, 59, 63, 66, 71, 76, 85, 86, 89, 92, 94, 96, 99}, 
  	27, 1159)
      fmt.Printf("TEST-6...%s\n", result)
      
      result = driver([]int{52, -56, -12, 78, 6, 32, 0, 36, 34, -54, -74, -32}, 
  	11, -45)
      fmt.Printf("TEST-7...%s\n", result)
      
      result = driver([]int{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, 1, 1, 1, 1, 1}, 
  	15, -86)
      fmt.Printf("TEST-8...%s\n", result)
      
      result = driver([]int{10, 42, 50, 5, 74, 81, 30, 76, 6, 34, 86, 4, 77, 71, 96, 22, 34, 50, 35, 16, 60, 11, 21, 38}, 
  	13, 951)
      fmt.Printf("TEST-9...%s\n", result)
      
          
  }
source_py: def find_repetitive_element_1_n_1(arr, n):
      return (sum(arr) - (((n - 1) * n) // 2))
source_cpp: int find_repetitive_element_1_n_1(vector<int> arr, int n) {
    return accumulate(arr.begin(), arr.end(), 0 ) - ( ( n - 1 ) * n / 2 );
  }