title: Number Of Pairs In An Array Having Sum Equal To Product
signature: func numberOfPairsInAnArrayHavingSumEqualToProduct(a []int, n int) int {
source_py: def number_of_pairs_in_an_array_having_sum_equal_to_product(a, n):
      zero = 0
      two = 0
      for i in range(n):
          if (a[i] == 0):
              zero += 1
          if (a[i] == 2):
              two += 1
      cnt = (((zero * (zero - 1)) // 2) + ((two * (two - 1)) // 2))
      return cnt
source_cpp: int number_of_pairs_in_an_array_having_sum_equal_to_product(vector<int> a, int n) {
    int zero = 0, two = 0;
    for ( int i = 0;
    i < n;
    i ++ ) {
      if ( a [ i ] == 0 ) {
        zero ++;
      }
      if ( a [ i ] == 2 ) {
        two ++;
      }
    }
    int cnt = ( zero * ( zero - 1 ) ) / 2 + ( two * ( two - 1 ) ) / 2;
    return cnt;
  }