title: Find Repetitive Element 1 N 1 2
signature: func findRepetitiveElement1N12(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{2, 2, 4, 5, 5, 7, 7, 7, 8, 11, 14, 15, 18, 19, 20, 25, 25, 29, 29, 31, 32, 32, 33, 38, 42, 48, 52, 55, 60, 61, 63, 71, 74, 78, 82, 82, 84, 84, 87, 87, 88, 90, 93, 94, 94}, 
  	31, 52)
      fmt.Printf("TEST-0...%s\n", result)
      
      result = driver([]int{46, 2, 62, 60, 92, 4, 26, 66, 66, 90, 26, -14, 76, -20, -68}, 
  	8, 46)
      fmt.Printf("TEST-1...%s\n", result)
      
      result = driver([]int{0, 0, 0, 1, 1, 1, 1, 1}, 
  	4, 1)
      fmt.Printf("TEST-2...%s\n", result)
      
      result = driver([]int{87, 67, 11, 47, 64, 81, 94, 75, 58, 77, 18, 2, 85, 26, 6, 44, 55, 19, 46, 49, 5, 69, 44, 12, 42, 66, 46, 9, 26, 49, 68, 95, 6, 9, 11, 72, 5, 67}, 
  	34, 28)
      fmt.Printf("TEST-3...%s\n", result)
      
      result = driver([]int{-98, -94, -92, -82, -78, -64, -62, -58, -52, -44, -40, -38, -8, 6, 10, 20, 22, 28, 30, 30, 36, 54, 54, 58, 64, 68, 76, 78, 84, 88, 90, 94, 96}, 
  	29, -32)
      fmt.Printf("TEST-4...%s\n", result)
      
      result = driver([]int{1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 1}, 
  	17, 16)
      fmt.Printf("TEST-5...%s\n", result)
      
      result = driver([]int{1, 14, 15, 15, 21, 34, 38, 39, 41, 50, 60, 74, 96, 97}, 
  	7, 25)
      fmt.Printf("TEST-6...%s\n", result)
      
      result = driver([]int{96, -12, -16, -52}, 
  	3, 103)
      fmt.Printf("TEST-7...%s\n", result)
      
      result = driver([]int{0, 0, 0, 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}, 
  	21, 21)
      fmt.Printf("TEST-8...%s\n", result)
      
      result = driver([]int{66, 21, 21, 59, 78, 8, 46, 41, 16, 32, 97, 93, 32, 86, 91, 61, 67, 61, 97, 49, 66, 35, 24, 35, 65, 45, 83}, 
  	25, 9)
      fmt.Printf("TEST-9...%s\n", result)
      
          
  }
source_py: def find_repetitive_element_1_n_1_2(arr, n):
      res = 0
      for i in range(0, (n - 1)):
          res = ((res ^ (i + 1)) ^ arr[i])
      res = (res ^ arr[(n - 1)])
      return res
source_cpp: int find_repetitive_element_1_n_1_2(vector<int> arr, int n) {
    int res = 0;
    for ( int i = 0;
    i < n - 1;
    i ++ ) res = res ^ ( i + 1 ) ^ arr [ i ];
    res = res ^ arr [ n - 1 ];
    return res;
  }