title: Non Repeating Element
signature: pub fn non_repeating_element(arr: Vec<i32>, n: i32) -> i32 {
test_code: use std::collections::HashMap;
  use std::collections::HashSet;
  use std::cmp::*;
  use std::collections::*;
  use std::fmt::*; 
  
  
  // SOLUTION CODE
  // ============================================
  PLACEHOLDER_CODE_BODY
  
  // TESTING CODE 
  // ============================================
  pub fn validate_solution(actual: i32, expected: i32)->bool{
  return actual==expected
  }
  pub fn driver(arr: Vec<i32>, n: i32, expected: i32)->String{
      if validate_solution(PLACEHOLDER_FN_NAME(arr, n), expected) {
        return "PASSED".to_string();
      };
      return "FAILED".to_string();
  
  }
  
  fn main() {
      println!("TEST-0...{}", driver(
        Vec::from([1, 2, 3, 4, 6, 6, 7, 9, 10, 13, 16, 23, 30, 32, 36, 42, 42, 43, 44, 47, 48, 48, 49, 52, 52, 53, 55, 56, 58, 59, 60, 60, 63, 67, 68, 68, 74, 75, 76, 80, 81, 81, 83, 83, 86, 87, 91, 92, 97]), 47, 
        1
      ));
      
      println!("TEST-1...{}", driver(
        Vec::from([-96, -46, -86, 56, -72, 50, 18, 8, 50]), 8, 
        -96
      ));
      
      println!("TEST-2...{}", driver(
        Vec::from([0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]), 14, 
        -1
      ));
      
      println!("TEST-3...{}", driver(
        Vec::from([19, 10, 49, 40, 34, 21, 63, 51]), 5, 
        19
      ));
      
      println!("TEST-4...{}", driver(
        Vec::from([-96, -96, -90, -88, -88, -84, -80, -76, -68, -64, -64, -52, -52, -52, -52, -50, -50, -48, -48, -40, -32, -26, -24, -22, -20, -14, -12, 0, 6, 8, 10, 20, 24, 28, 34, 36, 54, 60, 60, 60, 68, 74, 74, 74, 84, 88, 94]), 27, 
        -90
      ));
      
      println!("TEST-5...{}", driver(
        Vec::from([1, 0, 0, 1, 0, 1, 1, 1, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 1, 1, 0, 1, 0, 0, 0]), 19, 
        -1
      ));
      
      println!("TEST-6...{}", driver(
        Vec::from([1, 2, 3, 10, 15, 21, 28, 36, 41, 44, 45, 47, 72, 77, 77, 79, 85]), 15, 
        1
      ));
      
      println!("TEST-7...{}", driver(
        Vec::from([42, -84, 42, 36, -10, 24, -62, 60]), 7, 
        -84
      ));
      
      println!("TEST-8...{}", driver(
        Vec::from([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, 1, 1, 1, 1, 1, 1, 1]), 35, 
        -1
      ));
      
      println!("TEST-9...{}", driver(
        Vec::from([2, 21, 42, 92, 65, 62, 75, 43, 81, 17, 92, 86, 37, 63, 27, 97, 24, 61, 85, 49, 84, 7, 14, 19, 60, 55, 68, 79, 8, 12, 75, 12, 92, 79, 42]), 27, 
        2
      ));
      
  }
source_py: def non_repeating_element(arr, n):
      for i in range(n):
          j = 0
          while (j < n):
              if ((i != j) and (arr[i] == arr[j])):
                  break
              j += 1
          if (j == n):
              return arr[i]
      return (- 1)
source_cpp: int non_repeating_element(vector<int> arr, int n) {
    for ( int i = 0;
    i < n;
    i ++ ) {
      int j;
      for ( j = 0;
      j < n;
      j ++ ) if ( i != j && arr [ i ] == arr [ j ] ) break;
      if ( j == n ) return arr [ i ];
    }
    return - 1;
  }