#include<iostream>
#include<assert.h>
using namespace std;

int binaty_search(int* arr, size_t n, int x)
{ 
  assert(arr);
  int left = 0;
  int right = n - 1;

  while (left <= right)
  {
    int mid = (left + right) / 2;
    if (x < arr[mid])
    {
      right = mid-1;
    }
    else if (x > arr[mid])
    {
      left = mid+1;
    }
    else
    return mid;
  }
  return -1;
}

int main()
{
  int arr[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
  cout << binaty_search(arr, sizeof(arr) / sizeof(int), 0) << endl;
  cout << binaty_search(arr, sizeof(arr) / sizeof(int), 1) << endl;
  cout << binaty_search(arr, sizeof(arr) / sizeof(int), 2) << endl;
  cout << binaty_search(arr, sizeof(arr) / sizeof(int), 3) << endl;
  cout << binaty_search(arr, sizeof(arr) / sizeof(int), 4) << endl;
  cout << binaty_search(arr, sizeof(arr) / sizeof(int), 5) << endl;
  cout << binaty_search(arr, sizeof(arr) / sizeof(int), 6) << endl;
  cout << binaty_search(arr, sizeof(arr) / sizeof(int), 7) << endl;
  cout << binaty_search(arr, sizeof(arr) / sizeof(int), 8) << endl;
  cout << binaty_search(arr, sizeof(arr) / sizeof(int), 9) << endl;
  cout << binaty_search(arr, sizeof(arr) / sizeof(int), 10) << endl;
    return 0;
}

#include<iostream>
#include<assert.h>
using namespace std;

int binaty_search(int* arr, size_t n, int x)
{
  assert(arr);
  int left = 0;
  int right = n;

  while (left < right)
  {
    int mid = (left + right) / 2;
    if (x < arr[mid])
    {
      right = mid;
    }
    else if (x > arr[mid])
    {
      left = mid + 1;
    }
    else
      return mid;
  }
  return -1;
}
int main()
{
  int arr[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
  cout << binaty_search(arr, sizeof(arr) / sizeof(int), 0) << endl;
  cout << binaty_search(arr, sizeof(arr) / sizeof(int), 1) << endl;
  cout << binaty_search(arr, sizeof(arr) / sizeof(int), 2) << endl;
  cout << binaty_search(arr, sizeof(arr) / sizeof(int), 3) << endl;
  cout << binaty_search(arr, sizeof(arr) / sizeof(int), 4) << endl;
  cout << binaty_search(arr, sizeof(arr) / sizeof(int), 5) << endl;
  cout << binaty_search(arr, sizeof(arr) / sizeof(int), 6) << endl;
  cout << binaty_search(arr, sizeof(arr) / sizeof(int), 7) << endl;
  cout << binaty_search(arr, sizeof(arr) / sizeof(int), 8) << endl;
  cout << binaty_search(arr, sizeof(arr) / sizeof(int), 9) << endl;
  cout << binaty_search(arr, sizeof(arr) / sizeof(int), 10) << endl;
    return 0;
}

#include<iostream>
#include<assert.h>
using namespace std;

int binaty_srarch(int* arr, int x, int left, int right)
{
  assert(arr);
  int mid;
  if (left <= right)
  {
    mid = (left + right) / 2;
    if (arr[mid] == x)
    {
      return mid;
    }
    else
    if (x < arr[mid])
    {
      return binaty_srarch(arr, x, left, right - 1);
    }
    else if (x>arr[mid])
    {
      return binaty_srarch(arr, x, left + 1, right);
    }
  }
  return -1;
}

int main()
{
  int arr[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
  cout << binaty_srarch(arr, 0, 0, (sizeof(arr) / sizeof(int)) - 1) << endl;
  cout << binaty_srarch(arr, 1, 0, (sizeof(arr) / sizeof(int)) - 1) << endl;
  cout << binaty_srarch(arr, 2, 0, (sizeof(arr) / sizeof(int)) - 1) << endl;
  cout << binaty_srarch(arr, 3, 0, (sizeof(arr) / sizeof(int)) - 1) << endl;
  cout << binaty_srarch(arr, 4, 0, (sizeof(arr) / sizeof(int)) - 1) << endl;
  cout << binaty_srarch(arr, 5, 0, (sizeof(arr) / sizeof(int)) - 1) << endl;
  cout << binaty_srarch(arr, 6, 0, (sizeof(arr) / sizeof(int)) - 1) << endl;
  cout << binaty_srarch(arr, 7, 0, (sizeof(arr) / sizeof(int)) - 1) << endl;
  cout << binaty_srarch(arr, 8, 0, (sizeof(arr) / sizeof(int)) - 1) << endl;
  cout << binaty_srarch(arr, 9, 0, (sizeof(arr) / sizeof(int)) - 1) << endl;
  cout << binaty_srarch(arr, 10, 0, (sizeof(arr) / sizeof(int)) - 1) << endl;

  return 0;
}