title: Count Index Pairs Equal Elements Array
signature: pub fn count_index_pairs_equal_elements_array(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([4, 6, 9, 16, 16, 21, 36, 41, 58, 60, 62, 73, 77, 81, 95]), 12, 
        1
      ));
      
      println!("TEST-1...{}", driver(
        Vec::from([-86, -72, -26, -34, 18, -62, -66]), 3, 
        0
      ));
      
      println!("TEST-2...{}", driver(
        Vec::from([1]), 0, 
        0
      ));
      
      println!("TEST-3...{}", driver(
        Vec::from([16]), 0, 
        0
      ));
      
      println!("TEST-4...{}", driver(
        Vec::from([-88, -80, -72, -68, -64, -26, 4, 14, 16, 22, 30, 32, 60, 74, 82]), 11, 
        0
      ));
      
      println!("TEST-5...{}", driver(
        Vec::from([0, 0, 1, 1, 1, 0, 1, 0, 0, 0, 1]), 9, 
        16
      ));
      
      println!("TEST-6...{}", driver(
        Vec::from([3, 9, 10, 12, 17, 23, 27, 29, 42, 44, 59, 61, 71, 76, 78, 82, 84, 84, 89, 90, 93, 93, 97, 97]), 15, 
        0
      ));
      
      println!("TEST-7...{}", driver(
        Vec::from([68, -40, -46, -20, -64, 90]), 5, 
        0
      ));
      
      println!("TEST-8...{}", driver(
        Vec::from([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]), 15, 
        61
      ));
      
      println!("TEST-9...{}", driver(
        Vec::from([99, 17, 94, 43, 97, 17, 11, 58, 75, 94, 37, 22, 54, 31, 41, 4, 55, 69, 92, 80, 45, 97, 16, 33, 36, 17, 43, 82, 81, 64, 22, 65, 85, 44, 47, 14]), 23, 
        3
      ));
      
  }
source_py: def count_index_pairs_equal_elements_array(arr, n):
      ans = 0
      for i in range(0, n):
          for j in range((i + 1), n):
              if (arr[i] == arr[j]):
                  ans += 1
      return ans
source_cpp: int count_index_pairs_equal_elements_array(vector<int> arr, int n) {
    int ans = 0;
    for ( int i = 0;
    i < n;
    i ++ ) for ( int j = i + 1;
    j < n;
    j ++ ) if ( arr [ i ] == arr [ j ] ) ans ++;
    return ans;
  }