title: Find The First Missing Number
signature: int findTheFirstMissingNumber(vector<int> array, int start, int end_arg2) {
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> array, int start, int end_arg2, int expected){
      try
      {
          if (validateSolution(PLACEHOLDER_FN_NAME(array, start, end_arg2), 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({3, 6, 7, 9, 11, 14, 18, 30, 30, 32, 32, 34, 37, 44, 45, 45, 48, 48, 48, 52, 58, 60, 63, 67, 69, 69, 81, 83, 87, 89, 97, 99}, 24, 18, 19); 
      cout << "TEST-" << 0 << "..."
           <<  result
           << "\n";
  
      result = driver({88, -62, 16, 80, 66, 78, 88, 38, 52, -96, 48, 98, 96, -62, 18, 34, -58, 30, -10, 26, -98, 48, -96, 4, 92, 36, 36, -36, -32, -70, 62, -58, -58, -84, 86, -98}, 19, 26, 19); 
      cout << "TEST-" << 1 << "..."
           <<  result
           << "\n";
  
      result = driver({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, 1, 1, 1, 1, 1, 1, 1, 1}, 26, 28, 26); 
      cout << "TEST-" << 2 << "..."
           <<  result
           << "\n";
  
      result = driver({79, 99, 79, 85, 61, 58, 62, 61, 39, 87, 39, 74, 36, 70, 30, 43, 20, 52, 54, 50, 81, 98, 42}, 20, 20, 20); 
      cout << "TEST-" << 3 << "..."
           <<  result
           << "\n";
  
      result = driver({-98, -72, -46, -44, -42, -40, -16, -4, 62, 70, 74}, 8, 10, 8); 
      cout << "TEST-" << 4 << "..."
           <<  result
           << "\n";
  
      result = driver({1, 1, 0, 1, 0, 0, 0, 0, 1, 1, 0, 1, 0, 1, 1, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0}, 26, 23, 24); 
      cout << "TEST-" << 5 << "..."
           <<  result
           << "\n";
  
      result = driver({58}, 0, 0, 0); 
      cout << "TEST-" << 6 << "..."
           <<  result
           << "\n";
  
      result = driver({4, -84, -42, 12, -50, 42, -36, -38, -36, 98, -2, 20, 6, -96, -78, 24, 34, 88, 0, 74, 0, -8, -86, -68, -42, 98, -26, 86, -70, -32, -82, 78, 46, 58, 84, 4, -60, -90, -52, -78}, 37, 31, 32); 
      cout << "TEST-" << 7 << "..."
           <<  result
           << "\n";
  
      result = driver({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}, 28, 28, 28); 
      cout << "TEST-" << 8 << "..."
           <<  result
           << "\n";
  
      result = driver({8}, 0, 0, 0); 
      cout << "TEST-" << 9 << "..."
           <<  result
           << "\n";
  
      return 0;
  }
source_py: def find_the_first_missing_number(array, start, end):
      if (start > end):
          return (end + 1)
      if (start != array[start]):
          return start
      mid = int(((start + end) / 2))
      if (array[mid] == mid):
          return find_the_first_missing_number(array, (mid + 1), end)
      return find_the_first_missing_number(array, start, mid)
source_cpp: int find_the_first_missing_number(vector<int> array, int start, int end) {
    if ( start > end ) return end + 1;
    if ( start != array [ start ] ) return start;
    int mid = ( start + end ) / 2;
    if ( array [ mid ] == mid ) return find_the_first_missing_number ( array, mid + 1, end );
    return find_the_first_missing_number ( array, start, mid );
  }