title: Count Subarrays Equal Number 1S 0S
signature: int countSubarraysEqualNumber1S0S(vector<int> arr, int n) {
test_code: #include <algorithm>
  #include <assert.h>
  #include <cstdlib>
  #include <iostream>
  #include <map>
  #include <set>
  #include <string>
  #include <tuple> 
  #include <unordered_map>
  #include <vector>
  #include <math.h>
  #include <cmath>
  #include <bits/stdc++.h>
  #include <numeric>
  #include <functional>
  
  using namespace std;
  
  // SOLUTION CODE
  // ============================================
  PLACEHOLDER_CODE_BODY
  
  // TESTING CODE 
  // ============================================
  bool validateSolution(int actual, int expected){
      return actual == expected;
  }
  
  string driver(vector<int> arr, int n, int expected){
      try
      {
          if (validateSolution(PLACEHOLDER_FN_NAME(arr, n), expected)){
              return "PASSED";
          }
          return "FAILED";
      }
      catch (const std::overflow_error& exception_obj)
      {
          return typeid(exception_obj).name();
      }
      catch (const std::runtime_error& exception_obj)
      {
          return typeid(exception_obj).name();
      }
      catch (const std::exception& exception_obj)
      {
          return typeid(exception_obj).name();
      }
      catch (...)
      {
          return "UNK_ERROR";
      }
  }
  
  int main() {
      string result = "";
  
      result = driver({2, 12, 18, 19, 19, 20, 20, 21, 25, 29, 38, 54, 54, 71, 72, 72, 74, 75, 77, 78, 80, 80, 81, 84, 97, 97}, 24, 0); 
      cout << "TEST-" << 0 << "..."
           <<  result
           << "\n";
  
      result = driver({10, 70, 24, -38, 32, -68, 88, -28, -24, -70, -64, 50, -30, 64, 54, -6, 18, -30, -30, -62, -10, 94, -54, -22, -88, 96, 22, 26, -92, -40, -76, 46, 36, 30, 24, -52, 0}, 24, 1); 
      cout << "TEST-" << 1 << "..."
           <<  result
           << "\n";
  
      result = driver({0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1}, 11, 3); 
      cout << "TEST-" << 2 << "..."
           <<  result
           << "\n";
  
      result = driver({66, 50, 17, 15, 86, 84, 87, 24, 81, 23, 71, 31, 13, 72, 58, 19, 29, 28, 40, 14, 48, 48, 81, 4, 52, 88, 54, 56, 10, 12, 58, 55, 7, 66, 15, 73, 22, 2, 20, 27, 57, 56, 56, 31, 9, 55}, 40, 0); 
      cout << "TEST-" << 3 << "..."
           <<  result
           << "\n";
  
      result = driver({-98, -62, -60, 16, 78, 82}, 5, 0); 
      cout << "TEST-" << 4 << "..."
           <<  result
           << "\n";
  
      result = driver({1, 0, 1}, 2, 1); 
      cout << "TEST-" << 5 << "..."
           <<  result
           << "\n";
  
      result = driver({2, 31, 34, 64}, 2, 0); 
      cout << "TEST-" << 6 << "..."
           <<  result
           << "\n";
  
      result = driver({-70, 90, -10, -64, -76, -74, -12, -44, -48, -54, 76, -78, 8, 0, 0, 78, -28, 6, 98, -84, 60, 60, 2, 48, -96, -28, -78, -76, -56, -26, -60, 50, 44, 34, -90, 80, -30, -98, 62, 36, -46, -72}, 25, 2); 
      cout << "TEST-" << 7 << "..."
           <<  result
           << "\n";
  
      result = driver({1, 1, 1}, 1, 0); 
      cout << "TEST-" << 8 << "..."
           <<  result
           << "\n";
  
      result = driver({37, 70, 80, 61, 86, 10, 17, 98, 54, 89, 87, 84, 11, 55, 3, 52, 4, 90, 98, 31, 20, 62, 71, 58, 58, 6, 92, 5, 99, 99, 72, 40, 82, 54, 23, 19, 85, 91, 62, 98, 62, 72, 93, 74}, 27, 0); 
      cout << "TEST-" << 9 << "..."
           <<  result
           << "\n";
  
      return 0;
  }
source_py: def count_subarrays_equal_number_1s_0s(arr, n):
      um = dict()
      curr_sum = 0
      for i in range(n):
          curr_sum += ((- 1) if (arr[i] == 0) else arr[i])
          if um.get(curr_sum):
              um[curr_sum] += 1
          else:
              um[curr_sum] = 1
      count = 0
      for itr in um:
          if (um[itr] > 1):
              count += ((um[itr] * int((um[itr] - 1))) / 2)
      if um.get(0):
          count += um[0]
      return int(count)
source_cpp: int count_subarrays_equal_number_1s_0s(vector<int> arr, int n) {
    unordered_map < int, int > um;
    int curr_sum = 0;
    for ( int i = 0;
    i < n;
    i ++ ) {
      curr_sum += ( arr [ i ] == 0 ) ? - 1 : arr [ i ];
      um [ curr_sum ] ++;
    }
    int count = 0;
    for ( auto itr = um . begin ( );
    itr != um . end ( );
    itr ++ ) {
      if ( itr -> second > 1 ) count += ( ( itr -> second * ( itr -> second - 1 ) ) / 2 );
    }
    if ( um . find ( 0 ) != um . end ( ) ) count += um [ 0 ];
    return count;
  }